Doutorado em Física

URI Permanente para esta coleção

http://repositorio.ufes.br/handle/10/17493

Nível: Doutorado
Ano de início: 2003
Conceito atual na CAPES: 4
Ato normativo: Parecer CES/CNE nº 487/2018, homologado pela Port. MEC 609, publicado no DOU em 18/03/2019.
Periodicidade de seleção: Semestral
Área(s) de concentração: Física
Url do curso: https://fisica.ufes.br/pt-br/pos-graduacao/PPGFis/detalhes-do-curso?id=1509

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A energia de Casimir e a energia de transição de fase Ferromagnética em Duplas Perovskquitas
(Universidade Federal do Espírito Santo, 2017-05-26) Rocha, Jefferson Rodrigues; Orlando, Marcos Tadeu D’Azeredo; Orlando, Marcos Tadeu DAzeredo; Nogueira, José Alexandre; Batista, Antonio Brasil; Soares, Jacyra Ramos; Orlando, Marcos Tadeu D’Azeredo; Justo Filho, João Francisco
This thesis is based on Bordag’s theory of Casimir energy. This proposal relates the Casimir energy between conductor plasma planes and the thermal energy in the transition in double ferromagnetic conductive perovskites. Using this association it was possible to calculate the critical temperature of Curie ???? relating the fraction of the energy between these materials and the parameters of Sommerfeld ?? of each compound. To evaluate experimentally our proposal we considered the transition temperatures ???? and the parameters of 3 samples: ????2??????????6,????2?? ????????6 e ????2?? ????????6.We have found that for these samples the distance ?? between the conducting planes is associated with the Curie temperature Tc. Our proposal for the calculation of ???? is consistent with the values found in the literature for samples with these characteristics (ferrometal and conductive). Based on our theory we proposed the preparation of a new sample that presented a parameter ?? similar to that of the sample ????2??????????6 thus generating a Curie temperature ???? ˜ 635??,namely:????1.8??0.2??????????6. This new compound is a double perovskite with ferromagnetic metallic characteristics and octahedral geometry formed by planes containing ??????6 and presenting ?? ?? = 635??.
A equação de Schroedinger em um cenário de comprimento mínimo.
(Universidade Federal do Espírito Santo, 2019-11-29) Goncalves, André Oakes de Oliveira; Nogueira, Jose Alexandre; https://orcid.org/0000-0003-0808-6235; http://lattes.cnpq.br/6774401855734421; https://orcid.org/0000-0002-7945-6494; http://lattes.cnpq.br/9182069049776501; Fabris, Julio Cesar; https://orcid.org/000000018880107X; http://lattes.cnpq.br/5193649615872035; Furtado, Raphael Goes; https://orcid.org/0000-0002-2616-4762; http://lattes.cnpq.br/7034365539639197; Dorsch, Glauber Carvalho; https://orcid.org/0000-0002-6177-366X; http://lattes.cnpq.br/2674910790826779; Constantinidis, Clisthenis Ponce; http://lattes.cnpq.br/1328163673123152; Spalenza, Wesley; Francisco, Ronald Oliveira; Marra, Valerio; https://orcid.org/0000000277731579; http://lattes.cnpq.br/6846011112691877
In order to quantize gravity several approaches have been proposed. It is interesting that all of them predict the existence of a minimal length in the nature. In this work, we carry out the quantization of the Schroedinger’s equation, that is, the transformation of the wave function into a field operator (second quantization), in a minimal-length scenario. In order to obtain the Schroedinger’s equation in minimal-length scenario we modify the de Broglie’s postulate, that is, the relation between the linear momentum and the wave vector is no longer linear. The Schroedinger’s equation obtained in this way is a differential equation of fourth order. For this reason, we study the classical field theory with derivatives of high-order, in particular the Noether’s Theorem and Ostrogradsky’s Method with aim of obtaining the conserved quantities and the Hamiltonian of the system. Although the Schroedinger’s equation permits the quantization using commutation or anti-commutation relations, we only employ the commutation relation between create and annihilation operators
A Quantização da Gravitação em 3D com Constante Cosmológica Positiva
(Universidade Federal do Espírito Santo, 2012-07-31) Almaraz, Zui Agustin Oporto; Constantinidis, Clisthenis Ponce; Piguet, Olivier; Vanzella, Daniel Augusto Turolla; Ribeiro, Maria Cristina Batoni Abdalla; Alvarenga, Flávio Gimenes; Gomes, Jose Francisco; Gonçalves, Sergio Vitorino de Borba
It was shown by Bonzom and Livine that 2+1 gravity with cosmological constant contains an ambiguity that depends on a Barbero–Immirzi-like parameter ? known from 4D gravity. Based on this fact, we showed that, for the ? > 0 case, the Lorentzian theory can be partially reduced, thanks to a suitable gauge fixing, to a Chern–Simons theory with compact gauge group SU(2). Then we revised already known loop quantization of Chern–Simons theory for the case of a space with the topology of a cylinder. Finally we construct a quantum observable which, despite having a not trivial spectrum at the quantum level, it corresponds to a classical quantity identically null.
Abordagem relativística para o átomo de hidrogênio em um cenário de comprimento mínimo introduzido pela álgebra Lorentz-covariante de Quesne-Tkachuk
(Universidade Federal do Espírito Santo, 2013-11-29) Francisco, Ronald Oliveira; Fabris, Júlio César; Nogueira, José Alexandre; Helayel Neto, José Abdalla; Bazeia Filho, Dionisio; Rodrigues, Davi Cabral
One of the reasons for gravity can not be included in the standard model is its non-renormalizability. Almost all the proposals for the quantization of gravity leads to existence of a minimal length which acts as a natural regulator. That effect suggests a generalized uncertaintly relations between position and momentum operators what results in a modified commutation relation between these operators, and thus changing the whole structure of quantum mechanics. In this work we calculate the magnitude of this minimum length through the energy of the ground state of the hydrogen atom in Dirac’s theory, based on the Quesne-Tkachuck commutation relation. Comparing with experimental data, we obtained the value of the minimum length is orders of magnitude less than or equal to 10-20m
Algoritmos de amostragem por rejeição dinâmica aplicados a busca descentralizada em redes de mundo pequeno com topologia fractal
(Universidade Federal do Espírito Santo, 2021-11-23) Amaral, Leonardo Aguiar do; Belich Junior, Humberto; https://orcid.org/0000-0002-8795-1735; http://lattes.cnpq.br/3879935393431243; https://orcid.org/0000-0001-8951-4304; http://lattes.cnpq.br/3747190706760201; Soares, Thales Costa; https://orcid.org/0000-0001-8734-6642; http://lattes.cnpq.br/4676057702132305; Canal Neto, Antônio; https://orcid.org/0000-0002-8556-618X; http://lattes.cnpq.br/9283775492064031; Spalenza, Wesley; https://orcid.org/0000-0001-9644-3938; http://lattes.cnpq.br/2687428810786056; Mota, Vinicius Candido; https://orcid.org/0000000183680803; http://lattes.cnpq.br/4038237972209273; Favarato, Cássio Cecato; https://orcid.org/0000-0002-7599-595X; http://lattes.cnpq.br/0364649580177297
In this research, we study Kleinberg’s navigation in small-world networks using the dynamic rejection sampling algorithm proposed by Mathieu and Comte. Unlike conventional techniques, this approach dispenses with the use of periodic boundary conditions that deform the lattice and convert it into a toroid. Instead, acceptance masks are used superimposed on the studied square network to offer an additional acceptance criterion for the acquisition of long-range links, without violating the fundamental precepts that govern the statistical distribution of these connections, resulting in a drastic drop in the complexity of the algorithm. This work aims to extend Mathieu and Comte’s approach to networks with fractal topology (Sierpinski’s Square), this is done through the development of an auxiliary computational routine (fractal_search) which makes fractal geometry detectable to acceptance masks. This is a step of great relevance for the entire process regarding the complexity of the algorithm since the knowledge accumulated in the literature in the last decade indicates that the emergence of routing in fractal networks requires that they have extremely large sizes. Our routine was designed to operate recursively and harmonically with fractal self-similarity, which guarantees a performance compatible with the tasks it will perform during the simulation. The approach adopted in conducting this work was consistent with the forecasts and results already consolidated and published in journals specialized in the field of network science, such as the existence of a clustering exponent that minimizes the delivery time, when it assumes values identical to the dimension of the analyzed network (αmin = df ), besides the appearance of the proportionality of the delivery time with the logarithm of the network size (T ∼ ln2L). It was also demonstrated that the number of realizations (R), used to compose the sampling space of the statistical analysis of the simulation, and the network size (L), have interdependence and have a significant impact on the processing time. Finally, we performed a performance test using the execution time as a comparative parameter, which demonstrated the superiority of the proposed method compared to traditional methods.
Análise Hamiltoniana de Teorias de Gravitação pela Abordagem Simplética.
(Universidade Federal do Espírito Santo, 2021-06-17) Galvão Junior, Mariniel Souza; Rodrigues, Davi Cabral; https://orcid.org/0000000316835443; http://lattes.cnpq.br/5465449494182034; https://orcid.org/0000-0003-2260-5222; http://lattes.cnpq.br/2242425021389961; Fabris, Júlio César; https://orcid.org/000000018880107X; http://lattes.cnpq.br/5193649615872035; Neto, Nelson Pinto; https://orcid.org/0000-0001-6713-5290; http://lattes.cnpq.br/6196081550581346; Rocha Junior, Roldão da; https://orcid.org/0000-0003-3978-532X; http://lattes.cnpq.br/6017951215928479; Guimarães, Marcelo Santos; https://orcid.org/0000-0003-0057-148X; http://lattes.cnpq.br/5257334599729020; Sotkov, Galen Mihaylov; https://orcid.org/0000-0002-7276-016X; http://lattes.cnpq.br/6372536076880230
We show how to systematically apply the Faddeev-Jackiw symplectic method to General Relativity (GR), GR extensions and tetrad gravity coupled to fermions. We also develop a completely symplectic analysis for the computing of gauge symmetries and apply the results for GR. This provides a new coherent frame for Hamiltonian analyses of gravitational theories. The emphasis is on the classical dynamics, uncovering the constraints, the gauge transformations, in and off-shell, and the number of degrees of freedom; but the method results are also relevant for canonical quantization approaches. We clarify subtleties of the symplectic approach and comment on previous symplectic-based Hamiltonian analyses of extended theories of gravity, pointing out that the present approach is systematic, complete and robust.
Análise perturbativa em modelos cosmológicos fantasmas
(Universidade Federal do Espírito Santo, 2010-02-19) Jardim, Deborah Faragó; Fabris, Júlio César; Tonini, Eduardo Valentino; Dito, Giuseppe; Silva, Saulo Carneiro de Souza; Gonçalves, Sergio Vitorino de Borba; Zimdahl, Winfried Ernst Wilhelm
Dark energy models have became extensively studied in recent years. Earlier proposals have emerged this century to describe the Universe by means of a fluid whose equation of state was breaking with the paradigm imposed by the standard cosmology. Fluid of this kind require to violate some energy conditions and have a very peculiar behavior, denominated for this reason "phantom fluid". This work investigates the structures formation through the study of cosmological perturbations in Universe which scenario is the phantom cosmology. They have proposed two models, the first them by solving the perturbed equations for scalar modes, using a hydrodynamic and fields representation for the fluid and then making the asymptotic behavior analysis. The second model is a composite of two fluids, one component of pressureless matter and another with negative pressure, represented by a self-interacting scalar field . In this case, the solution was obtained by numerical calculation. Results were confronted with the observational data and it showed models phantom of this nature are quite possible and its open a new window of research
Bases gaussianas geradas com os métodos Monte Carlo Simulated Annealing e Particle Swarm Optimization.
(Universidade Federal do Espírito Santo, 2017-10-03) Reis, Thiago Mello dos; Alfonso, Jorge Luis Gonzalez; Caetano, Edson Passamani; Continentino, Mucio Amado; Nascimento, Valberto Pedruzzi; Macedo, Waldemar Augusto de Almeida
The Monte Carlo Simulated Annealing and Particle Swarm Optimization methods were used to generate adapted Gaussian basis set for the atoms from H to Ar, in the ground state. A study about the e ciency and the reliability of each method was performed. In order to check the reliability of the proposed methods, we perform an speci c study considering a training set of 15 atoms, namely: N, Mg, Al, Cl, T i, N i, Br, Sr, Ru, P d, Sb, Cs, Ir, Tl, At. First of all, the Improved Generator Coordinate Hartree-Fock Method was applied to generate adapted basis which was used as start point to generate new Gaussian basis sets. After that, the Monte Carlo Simulated Annealing and Particle Swarm Optimization methods were developed from parallel studies, however following the same procedure so as we could have the possibility to compare them. Previously applying of the developed methods we perform some calibrations in order to de ne the values of the parameters of the algorithms; we perform studies about annealing schedules (for the Monte Carlo Simulated Annealing method), the total of swarm's particle (for the Particle Swarm Optimization method), and the total of steps for each algorithm. After the calibration procedure, both methods were applied, with the variational principle, to the Hartree-Fock wave function to give us the fully optimized Gaussian basis sets. Next, the basis sets were contracted by considering the lowest total energy loss, prioritizing the contraction of the most internal exponents. The last two steps of our procedure were the addition of polarized and di use functions, respectively. These procedures were performed by using the methods which we developed in this work through calculations to the MP2 level. The basis sets that have been generated in this work were used in some atomic and molecular calculations; we compare such results with relevant results from literature. We veri ed that, if we consider the same computational e ciency for both Monte Carlo Simulated Annealing and Particle Swarm Optimization methods, there is a vi small di erence between them as regards the accuracy, so that by using the Monte Carlo Simulated Annealing method we obtain best results. When we compare the results of this work with those from literature we note similar results for the properties that were studied, however the proposed methods in this work are more e cient, and we can de ne a single total numbers of steps for the algorithms even though we are treating with di erent atomic systems. In addition, we verify that the proposed methods in this work are more accurate than other similar methods presented in the literature, in the task of nding the global minima of the uncontracted basis sets to HF level of theory. It will be necessary to perform additional studies to check the real relationship between the accuracy of the methods. We do not verify the in uence of several parameters of the Particle Swarm Optimization algorithm in this work. The fact that the developed methods in this work have been constructed through Double Zeta basis does not prevent them to be used for larger basis sets, the two methods are able to be applied to generate Gaussian basis sets in the atomic environment for Gaussian basis sets with di erent qualities
Bases gaussianas geradas em ambientes atômico e molecular
(Universidade Federal do Espírito Santo, 2014-09-19) Arruda, Priscilla Mendes; Canal Neto, Antônio; Jorge, Francisco Elias; Freitas, Jair Carlos Checon de; Poveda Calviño, Luis Argel; Campos, Cesar Turczyn
A Gaussian basis set of small size for the atoms from H through Ar was constructed from a single sequence of exponents of 19 Gaussian functions, based on the generator coordinate Hartree-Fock method. For each atom studied a segmented contraction scheme was proposed and polarization functions and di use functions were added. Applications of the new contracted and uncontracted basis sets for the the calculation of the equilibrium geometries and electric properties (electric dipole moments and polarizabilities) of various molecular systems were performed and comparisons were made between theoretical and experimental results. The universal Gaussian basis sets presented in this work (with and without contraction) are competitive when compared to adapted basis sets of similar size. The Monte Carlo simulated annealing method was adapted to optimize correlated Gaussian-type functions in non-relativistic molecular environments. Starting from an atom-centered atomic Gaussian basis set, the uncontracted functions were reoptimized in the molecular environments corresponding to the BF, CN -, CO, CO2, CS, H2O, N2 and NO+ systems. These new molecule-optimized basis sets, called hybrid-basis sets HXZP (X = D, T, Q, and 5), were used to calculate total energies, harmonic vibrational frequencies, equilibrium geometries, electric dipole moments, and polarizabilities, at correlated level of theory. The present methodology is a simple and e ective way to improve molecular correlated wave functions, without the need to enlarge the molecular basis set. This methodology was employed to generate hierarchical sequences of molecular basis sets with increasing size, which we used to obtain complete basis set limits. xv xvi Additionally, the Monte Carlo simulated annealing method was employed to generate a hierarchical sequence of molecule-optimized basis set to CN -, CO, CO2, CS, H2O, N2 and NO+ systems. In these basis sets, all exponents were optimized in the molecular environment. Contraction schemes were proposed to each studied system, resulting in a nal molecular basis set, which we called MXZP (X = D, T, and Q). We used this hierarchical sequence of basis set to calculate total energies, harmonic vibrational frequencies, equilibrium geometries, electric dipole moments, and polarizabilities, at correlated level of theory. Also, we used that hierarchical sequences of molecular basis sets to obtain complete basis set limits. We veri ed, for the studied systems, that the MXZP basis sets produced more suitable molecular properties than the corresponding HXZP basis sets
Buracos negros fantasmas.
(Universidade Federal do Espírito Santo, 2010-04-23) Rodrigues, Manuel Eleuterio; Fabris, Júlio César; Alvarenga, Flávio Gimenes; Mello, Eugênio Ramos Bezerra de; Piguet, Olivier; Sotomayor, Patrício Anibal Letelier
We obtain the general solution of the Einstein-(anti) Maxwell-(anti) Dilaton (EMD)theory for a static, spherically symmetric spacetime in four dimensions. In the phantom(anti) cases, we obtain new solutions with non-degenerate horizon and make the analysis oftheir causal structures. The causal structures of some solutions are exotics, some of themcan not be described in two-dimensional usual Penrose diagrams. We obtain also, usingthe method of Sigma model, new stationary solutions with axial symmetry, for Einstein-anti-Maxwell-Dilaton (E ¯MD) and Einstein-anti-Maxwell-Dilaton-Axion (E ¯MDA) theory.We analyse the causal structure of these new solutions.
Caracterização estrutural e magnética de filmes finos de Gd depositados por magnetron sputtering
(Universidade Federal do Espírito Santo, 2023-09-28) Bernardino, Simone Venturim; Nascimento, Valberto Pedruzzi; https://orcid.org/0000000295435335; http://lattes.cnpq.br/9908042258225541; https://orcid.org/0000-0002-7379-0109; http://lattes.cnpq.br/3397738163607593; Hneda, Marlon Luiz; Sousa, Marcos Antonio de; Scopel, Wanderla Luis; https://orcid.org/0000000220918121; http://lattes.cnpq.br/1465127043013658; Felix, Jorlandio Francisco
Initially, the structural and magnetic properties of thin gadolinium films with thicknesses of 20, 50 and 200 nm grown by a Magnetron Sputtering on (100) silicon substrate at room temperature have been investigated. Thus, among the three samples, the 200 nm thin gadolinium film excelled since it only presents a compact hexagonal phase with a strong preferential orientation of the (002) planes, higher Curie temperature value and higher saturation magnetization (55% higher than that obtained with a thickness of 50 nm). Therefore, the thickness of the deposited thin films was kept constant in 200 nm to study the changes of properties of the gadolinium films caused by the variation of the following growing experimental conditions: substrate temperature and application of the bias sputtering procedure before the deposition of the materials. A 3 nm thick platinum protective layer has been deposited on all gadolinium films to avoid the surface oxidation. The samples produced at 300 K or 673 K presented only the compact hexagonal phase or two polymorphic crystalline structures (compact hexagonal and face-centered cubic), respectively. In details, with increasing substrate temperature during the deposition, from 300 K to 673 K, it was found that: (i) the crystals of the compact hexagonal phase had their axes of crystalline symmetry preferentially reoriented from the perpendicular to the parallel direction to the film plane; (ii) it occurred the appearance of the face-centered cubic structure with (111) planes preferentially parallel to the film plane and (iii) there was an increase of the dispersion of the crystallite orientations for the two polymorphic structures. The samples showed thermal hysteresis of (6 ± 1) K close to room temperature as a consequence of the magnetocaloric effect. The analysis of the ferromagnetic resonance results showed that an in-plane magnetization is favored by the face-centered cubic phase and the (100) preferential crystalline orientation of the compact hexagonal structure. Finally, these results suggest that internal strains in the films can induce reorientation of crystalline axes and the appearance of the face-centered cubic phase, factors that can strongly influence the effective anisotropy of the thin film and make the magnetic analysis more complex, when compared to what occurs in the macroscopic dimension. This study brings new approaches to the structural and magnetic properties of gadolinium thin films that have aroused the interest of the scientific community in recent decades due to their application in magnetocaloric refrigerators, high resistance alloys, permanent magnets and magnetic resonance imaging contrast agents.
Conjunto de bases gaussianas de qualidade dupla zeta para os átomos de Rb até Xe
(Universidade Federal do Espírito Santo, 2010-09-28) Barros, Cezar Laurence; Canal Neto, Antônio; Jorge, Francisco Elias; Lima, Denise da Costa Assafrão de; Pires, José Maria; Castro, Marco Antônio de; Fonseca, Tertius Lima
All-electron contracted Gaussian basis set of double zeta valence quality plus polarization functions (DZP) for the atoms from Rb to Xe is presented. This set was augmented by addition of diffuse functions (s, p, d, and f symmetries) that were optimized for the anion ground states and that are critical for an accurate description of electron affinity, polarizabilities, optical rotation, and hydrogen bonding. Besides, Douglas-Kroll-Hess (DKH) basis set for fourth-row elements is reported. We have recontracted the original DZP basis set, i.e., the values of the contraction coefficients were re-optimized using the relativistic DKH Hamiltonian. This extends earlier works on segmented contracted DZ basis set for atoms HKr. Our sets along with ab initio methods and density functional theory were used to calculate ionization energies of some atoms and spectroscopic constants and static electric properties of a sample of molecules and, then, comparison with results obtained with other basis sets and with experimental data reported in the literature was done. One verifies that our results give good agreement with experimental and benchmark values
Conjuntos de bases gaussianas correlacionados não relativístico e relativístico : aplicação em cálculos de constantes espectroscópicas e de propriedades elétricas e magnéticas moleculares
(Universidade Federal do Espírito Santo, 2009-12-18) Camiletti, Giuseppi Gava; Jorge, Francisco Elias; Canal Neto, Antônio; Machado, Antonio Eduardo da Hora; Silva Filho, Eloi Alves da; Guimarães, Freddy Fernandes; Morigaki, Milton Koiti
Contracted basis set of double zeta (DZ) quality for the atoms from K to Kr is presented. It was determined from fully-optimized basis set of primitive Gaussian-type functions generated in atomic Hartree-Fock calculations. Sets of Gaussian polarization functions optimized at the Mfller-Plesset second-order level were added to the DZ basis set. This extends earlier work on segmented contracted DZ basis set for atoms H-Ar. From this set, using the BP86 non-hybrid and B3LYP hybrid functionals, dissociation energy, geometric parameters, harmonic vibrational frequency, and electric dipole moment of a set of molecules were calculated and compared with results obtained with other basis sets and with experimental data reported in the literature. In addition, 57Fe and 77Se nuclear magnetic resonance chemical shifts in Fe(C5H5)2, H2Se, and CSe2 were calculated using density functional theory and gauge-including atomic orbitals and, then, compared with theoretical and experimental values previously published in the literature. Except for chemical shift, one verifies that our results give the best agreement with experimental and benchmark values. Augmented Gaussian basis sets of double and triple zeta valence qualities plus polarization functions for the atoms K and from Sc to Zn are also presented. They were generated from the all-electron unaugmented sets by addition of diffuse functions (s, p, d, f, and g symmetries), that were optimized for the anion ground states. From these sets, HartreeFock, second-order Mfller-Plesset perturbation theory, and density functional theory electric dipole moment and dipole polarizability calculations for a sample of molecules were carried out. Finally, Douglas-Kroll-Hess (DKH) contracted Gaussian basis sets of double, triple, and quadruple zeta valence qualities plus polarization functions (XZP, X=D, T, and Q, respectively) for the atoms H, Li, Be, Na, and Mg and DZP and TZP for K-Zn are presented. xv They have been determined from the corresponding non-relativistic basis sets generated previously by Jorge et al. We have recontracted the original XZP basis sets, i.e., the values of the contraction coefficients were reoptimized using the relativistic DKH Hamiltonian. The scalar relativistic effect at the coupled-cluster level of theory on the ionization energy of some atoms and dissociation energy and geometric parameters for a sample of molecules is discussed. All results obtained in this work were compared with theoretical and experimental values available in the literature
Conjuntos de bases gaussianas de qualidade quádrupla zeta de valência para os átomos de Rb até Xe
(Universidade Federal do Espírito Santo, 2013-04-25) Ceolin, Geovane de Araujo; Jorge, Francisco Elias; Muniz, Eduardo Perini; Georg, Herbert de Castro; Pires, José Maria; Lopes, Juliana Fedoce; Suave, Rogério Netto
All-electron segmented contracted quadruple zeta valence plus polarization function (QZP) basis sets for the elements Rb-Xe were constructed to be used in conjunction with the non-relativistic and Douglas-Kroll-Hess (DKH) Hamiltonians. The QZP-DKH set is obtained from the original QZP basis set, i.e., the values of the contraction coefficients were reoptimized using the relativistic DKH Hamiltonian. This extends earlier works on segmented contracted QZ basis set for atoms H-Kr. At the Coupled Cluster level of theory, the convergence of atomic ionization energy as well as molecular spectroscopic constants as a function of basis set size is examined. Additional improvements on spectroscopic constants were achieved by applying corrections due to core-valence correlation and spin-orbit effects. This leads to estimates for the spectroscopic constants of various diatomics in gaseous phase. One verifies that the experimental and benchmark theoretical bond lengths, dissociation energies, and harmonic vibrational frequencies can be reproduced well with the QZP-DKH set. Augmented Gaussian basis set of quadruple zeta valence quality plus polarization functions for the atoms Rb and from Y to Xe is presented. It was were constructed from the all-electron unaugmented set by addition of diffuse functions (s, p, d, f, g, and h symmetries) that were optimized for the anion ground states. From this set, Hartree-Fock, second-order Mfller-Plesset perturbation theory, and density functional theory electric dipole moment and polarizabilities for a sample of molecules as well as for Agn (n = 4) clusters were calculated and compared with theoretical and experimental values available in the literature
Conjuntos de bases gaussianas para K até Kr e para Pt: aplicações em cálculos de propriedades moleculares
(Universidade Federal do Espírito Santo, 2013-03-04) Berredo, Ricardo Coelho de; Jorge, Francisco Elias; Canal Neto, Antônio; Lima, Denise da Costa Assafrão de; Santos, Hélio Ferreira dos; Mohallem, José Rachid
All-electron segmented contracted quadruple zeta valence plus polarization function (QZP) basis sets for the elements from K to Xe were constructed to be used in conjunction with the non-relativistic and Douglas-Kroll-Hess (DKH) Hamiltonians. The QZP-DKH set is obtained from the corresponding original QZP basis set, i.e., the values of the contraction coefficients were re-optimized using the relativistic DKH Hamiltonian. This extends earlier works on segmented contracted QZ basis set for atoms H–Ar. At the Coupled-Cluster level of theory, the convergence of atomic ionization energy as well as of molecular spectroscopic constants as a function of basis set size is examined. Additional improvements on spectroscopic constants were achieved by applying corrections due to core-valence correlation and spin-orbit effects. This leads to estimates for the spectroscopic constants of various diatomics in gaseous phase. One verifies that the experimental and benchmark theoretical bond lengths, dissociation energies, and harmonic vibrational frequencies can be reproduced well with the QZP-DKH set. Segmented all-electron contracted double zeta valence plus polarization function (DZP) basis sets for the Pt element were constructed for use along with the non-relativistic and DKH Hamiltonians. The DZP-DKH set is loosely contracted and thus offer computational advantages compared to the generally contracted relativistic basis sets, while their sufficiently small size allows it to be used in place of effective core potentials (ECP) for routine studies of molecules. Using the one-parameter hybrid functional mPW1PW, the performance of the basis sets is assessed for predicting the molecular structures and atomic charges of platinum(II) antitumor drugs, cisplatin and carboplatin. These results can be used as reference values to calibrate further ECP calculations. Despite their compact size, the DZP sets demonstrate consistent, efficient, and reliable performance and will be especially useful in calculations of molecular properties that require explicit treatment of the core electrons. With the purpose of having a better description of electron affinity, polarizabities, and hydrogen bonding, the DZP set was augmented with diffuse (s, p, and d symmetries) and polarization (f symmetry) functions that were optimized for the anion at the Hartree-Fock and Møller-Plesset second-order levels, respectively. From optimized relativistic geometries and using non-hybrid and hybrid functionals, the performance of the augmented DZP (ADZP) set is assessed for predicting static electric dipole moment and polarizability of PtH, PtH2, and antitumor drugs (cisplatin and carboplatin). Despite its compact size, the ADZP set demonstrates consistent, efficient, and reliable performance. ADZP electric property calculations showed to be as fast as those that use augmented ECP basis sets
Conjuntos de bases gaussianas segmentados para todos os elétrons para He, Ca, Sr, Ba e lantanídeos.
(Universidade Federal do Espírito Santo, 2019-11-29) Ferreira, Igor Badke; Jorge, Francisco Elias; https://orcid.org/0000000185483918; http://lattes.cnpq.br/1986882876847099; https://orcid.org/0000-0002-1678-8731; http://lattes.cnpq.br/8155176458674058; Braga, Joao Pedro; https://orcid.org/; http://lattes.cnpq.br/; Custodio, Rogerio; https://orcid.org/; http://lattes.cnpq.br/2887634760481905; Camiletti, Giuseppi Gava; https://orcid.org/0000-0002-7499-9932; http://lattes.cnpq.br/8736403052879718; Canal Neto, Antonio ; http://lattes.cnpq.br/9283775492064031
Non-relativistic and Douglas-Kroll-Hess (DKH) augmented basis sets (AXZP and AXZP-DKH) for He (X = D, T, Q and 5), Ca and Sr (X = D, T and Q), Ba (X= D and T), and lanthanides (X = D) are generated. These sets are appropriated to describe electrons away from the nuclei. Using the DKH augmented sets along with the B3LYP functional, bond lengths, dissociation energies, harmonic vibrational frequencies, adiabatic ionization potentials (Adiabatic Ionization Potencial, AIP) and electron affinities (Adiabatic Electron Affinity, AEA), and electric dipole moments for CaH, SrH, and BaH are computed. These results agree well with the most recent experimental and benchmark theoretical data published in the literature. The mean dipole polarizabilities reported in this work for some elements are close to the recommended values. Nonrelativistic and relativistic DKH segmented all-electron Gaussian basis sets of valence triple zeta quality plus polarization functions (TZP) for the lanthanides are developed. As some atomic and molecular properties depend on a good description of the electrons far from the nuclei, these basis sets are augmented with diffuse functions, giving rise to the augmented TZP (ATZP) and ATZP-DKH basis sets. At the DKH level of theory, the B3LYP hybrid functional in conjunction with the TZP-DKH basis set are used to calculate the atomic charges and valence orbital populations of the lanthanide and oxygen atoms, equilibrium bond lengths, and dissociation energies of the lanthanide monoxides. The DKH-B3LYP/ATZP-DKH polarizability of Yb and the DKH-M06/TZP-DKH first ionization energies of the lanthanides are also reported. Compared with the values obtained with a larger all-electron basis set and with theoretical and experimental data found in the literature, the results obtained by our compact basis sets are verified to be accurate and reliable. Unlike effective core potential valence basis sets, our basis sets can also be employed in molecular property calculations that involve the simultaneous treatment of core and valence electrons
Conjuntos de bases gaussianas segmentados para todos os elétrons para os elementos de Cs até Rn e de Th até Lr.
(Universidade Federal do Espírito Santo, 2017-02-06) Martins, Lucas Sousa Carvalho; Jorge, Francisco Elias; Morgon, Nelson Henrique; Canal Neto, Antônio; Freitas, Jair Carlos Checon de; Machado, Luiz Carlos
All-electron contracted Gaussian basis set of triple zeta valence quality plus polarization functions (TZP) for the elements Cs, Ba, La, and from Hf to Rn is presented. Douglas-Kroll-Hess (DKH) basis set for fifth-row elements is also reported. We have recontracted the original TZP basis set, i.e., the values of the contraction coefficients are re-optimized using the second-order DKH Hamiltonian. By addition of diffuse functions (s, p, d, f, and g symmetries), which are optimized for the anion ground states, an augmented TZP basis set is constructed. Using the Becke 3-parameter (exchange) and the Lee, Yang and Parr (correlation) functional (B3LYP), the performance of the TZP-DKH basis set is assessed for predicting atomic ionization energy as well as spectroscopy constants of some compounds. Segmented all-electron basis sets of valence double zeta quality plus polarization functions (DZP) for the elements from Ce to Lu are also generated to be used with the non-relativistic and DKH Hamiltonians. At the B3LYP level, the DZP-DKH atomic ionization energies and equilibrium bond lengths and atomization energies of the lanthanide trifluorides are evaluated and compared with benchmark theoretical and experimental data reported in the literature. Finally, for the actinides, two segmented all-electron basis sets of valence double zeta quality plus polarization functions (DZP) are developed. One of them must be used along with the non-relativistic Hamiltonian, whereas the other with the DKH one. For the actinide trichlorides, geometric parameters, atomic charges of the actinides, and populations for the actinide valence orbitals are calculated using the B3LYP functional in conjunction with the DZP-DKH basis set. For UCl3 and UF3, dissociation energies are also reported.Comparison with benchmark theoretical and experimental values found in the literature is carried out. It is verified that the performance of the relativistic compact size basis sets generated in this work are regular, efficient, and reliable. They will be extremely helpful on molecular property calculations that need explicitly to consider the core electrons.
Conjuntos de bases gaussianas: aplicações em cálculos de constantes espectroscópicas e rotação ótica
(Universidade Federal do Espírito Santo, 2012-12-14) Campos, Cesar Turczyn; Jorge, Francisco Elias; Schneider, Edgar; Pires, José Maria; Freitas, Luiz Carlos Gomide; Morigaki, Milton Koiti
Segmented all-electron contracted sextuple zeta valence plus polarization function (6ZP) basis sets for the elements from H to Ar were constructed to be used in conjunction with the nonrelativistic and Douglas-Kroll-Hess (DKH) Hamiltonians. The scalar relativistic effect at the coupled cluster (CC) level of theory on atomization energy for a sample of molecules was discussed. Additional improvements in the atomization energies were achieved by applying corrections due to core/valence correlation, atomic spin-orbit effects, and addition of tight d and f functions on second-row elements. This leads to estimates for the heat of formation of gaseous boron and carbon tetrafluoride. With the purpose to have a better description of some molecular properties, the non relativistic and relativistic segmented all-electron contracted double, triple, quadruple, quintuple, and sextuple zeta valence plus polarization function (XZP and XZP-DKH, X= D, T, Q, 5, and 6) basis sets for the elements from H to Ar were augmented with high-exponent d “inner polarization functions”, which were optimized in the molecular environment at the M?ller-Plesset secondorder level. At the CC level of theory, the effect of including tight d functions in these elements was found to be essential to improve the agreement between theoretical and experimental zero-point vibrational energy (ZPVE) and atomization energy. For all molecules studied, the ZPVE errors are always smaller than 0.5%. Additional improvements in the atomization energies were achieved by applying corrections due to core/valence correlation and atomic spin-orbit effects. This leads to estimates for the atomization energies of various compounds in gaseous phase. The largest error (1.2 kcal/mol) occurs for SiH4. Finally, using the hierarchical sequence of augmented XZP (AXZP, X = D, T, and Q) for the atoms from H to Ar in conjunction with the B3LYP, PBE1PBE, M06, and M06-2X functionals, a systematic study of Gaussian basis set convergence on frequency dependent optical rotation ([?]?) calculations of thirteen rigid chiral molecules at their equilibrium geometries were xvii reported. By direct calculations or by fitting the directly calculated values through one extrapolation scheme, estimates of complete basis set limits were obtained. These limits can be used as reference values to calibrate further density functional theory calculations
Conjuntos de bases segmentados para todos elétrons de qualidades dupla (Fr-Ac) e tripla (Fr-Lr) zeta de valência.
(Universidade Federal do Espírito Santo, 2019-11-28) Oliveira, Amanda Ziviani de; Jorge, Francisco Elias; https://orcid.org/0000000185483918; http://lattes.cnpq.br/1986882876847099; https://orcid.org/; http://lattes.cnpq.br/4468010051355057; Ceolin, Geovane de Araujo; https://orcid.org/; http://lattes.cnpq.br/2097843909201655; Comar Junior, Moacyr ; https://orcid.org/0000-0002-4400-6039; http://lattes.cnpq.br/3361280087783853; Macedo, Luiz Guilherme Machado de; https://orcid.org/; http://lattes.cnpq.br/3809730482457606; Scopel, Wanderla Luis; https://orcid.org/0000000220918121; http://lattes.cnpq.br/1465127043013658
Segmented all–electron Gaussian basis sets of valence double (Fr–Ac) and triple (Fr–Lr) zeta qualities plus polarization functions (DZP and TZP) were generated using the non-relativistic and Douglas–Kroll–Hess (DKH) Hamiltonians. In order to accurately describe the properties that depend on a good description of the electrons far away from the nuclei, the corresponding augmented sets (ADZP, ADZP–DKH, ATZP and ATZP–DKH) are also reported. For Fr, Ra and Ac, at the DKH2–B3LYP level, first atomic ionization energies, as well as bond lengths, dissociation energies, and polarizabilities of a sample of diatomic molecules containing these elements are calculated. From Th to Lr, for the actinide monoxides, bond distances, equilibrium dissociation energies, natural charges and populations of the valence orbitals of the actinides, and bond indices are computed with the B3LYP/TZP–DKH procedure. For Am and No, the B3LYP/ATZP–DKH static mean dipole polarizabilities are also computed. To assess the performance of these all–electron basis sets, comparison with theoretical and experimental data reported previously in the literature is done. It is verified that despite the small sizes of the basis sets, they are reliable and must be also helpful on calculations of properties involving simultaneously core and valence electrons
Controle das estruturas cristalinas e Anisotropias Magnéticas em filmes à base de Co e Gd
(Universidade Federal do Espírito Santo, 2015-12-11) Bertelli, Tiago Pulce; Caetano, Edson Passamani; Larica, Carlos; Pelegrini, Fernando; Pessoa, Marcio Solino; Sommer, Rubem Luis; Bueno, Thiago Eduardo Pedreira
In this work, we present a systematic investigation of the experimental parameters [inclination angle between the normal of the substrate plane and deposition flux direction a; angular velocity of the sample holder ?; magnetic field application during deposition HD; substrate temperature TS] on the values of the cubic HKC, uniaxial HKU and exchange bias HEB anisotropy of Co and Gd thin films, bilayers of Co/IrMn and IrMn/Gd and trilayers of Co/IrMn/Gd prepared by DC Magnetron Sputtering. Using the X-ray diffraction technique, it is demonstrated that, regardless the values of a, ? and HD parameters, Co films were deposited on the Ta seed layer oriented in the [111] direction with face centered cubic (fcc) structure. For the Gd films grown on the Ta seed layer, it was shown that as higher is the TS value, larger is the internal stress in Gd films; a feature that favors stabilization of the fcc-type phase for Gd thickness tGd of 10 nm. The increase of tGd or decrease of TS value causes structural relaxation to the hexagonal close packed hcp phase; it occurs on top of fcc-type Gd structure grown on Ta seed layer. Concerning the anisotropy fields (measured by ferromagnetic resonance technique FMR), it is demonstrated that due to the oblique deposition a ? 0°, one can control the HKU field of Co film. Specifically, for the Co film prepared at a = 55°, ? = 0 rpm and HD nulo, a maximum value of HKU = 72 Oe was obtained. It was possible to project samples with pure cubic or uniaxial and combined HKC + HKU fields by using oblique deposition for low a values (22 = a = 40°) with different rotation speeds ? (0, 30 and 40 rpm) of the sample holder during Co depositions. It was found that the HKC field remains approximately constant (? 2.8 Oe) regardless of a, ? and HD values, while the HKU field linearly decreases with the increasing of the angular velocity ? at a rate of 0.35 Oe/rpm (sample-holder central position: 15.7 = HKU = 1.4 Oe and sample-holder edge positions: 20.6 = HKU = 6.5 Oe for the range 0 = ? = 40 rpm, respectively). Using magnetometry measurements, it is shown that the fcc phase of Gd presents magnetization of 175 emu/cm3 and coercive field of 100 Oe, nearly constants in a wide temperature range (10 = T = 400 K), while the hcp Gd phase shows large coercive fields (HC = 480 Oe) and saturatation magnetization (MS = 640 emu/cm3 ) at 60 K, before spin reorientation phenomenon. Comparing Co/IrMn bylayers prepared with HD = 0 and HD ? 0 (applied to the film plane), it wasfound a significant increase of both uniaxial HKU (13 ? 33 Oe), and exchange bias HEB (33 ? 55 Oe) fields for samples located at the sample-holder central position. In addition, for bilayers samples fabricated at the sample-holder edge positions, the rotation of the xii sample enhances much more the HKU value (130%); an effect associated with the variation of a angle during the sample rotation. For Co/IrMn/Gd trilayers prepared at the sample-holder edges, the HKU field presents an anomalous increase (~ 45 ? ~ 220 Oe, 5 times bigger), accompanied by an increase of 45% in the HEB field related to the Co/IrMn interface (~ 55 ? ~ 80 Oe). This behavior may be due to the presence of ferromagnetic Gd deposited on top of texturized [111] IrMn layer. In fact, it diserves additional investigations since its physical origin is not yet understood.

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