Física

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http://repositorio.ufes.br/handle/10/17492
Programa de Pós-Graduação em Física

Centro: CCE
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URL do programa: http://www.fisica.ufes.br/pos-graduacao/PPGFis

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    Conjuntos de bases ZORA de qualidades 5 e 6 zeta de valência para o hidrogênio até o argônio : aplicação em cálculos de propriedades atômicas e moleculares
    (Universidade Federal do Espírito Santo, 2024-08-23) Sampaio, Gabriel Rodrigues do Carmo; Co-orientador1; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador2; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador3; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador4; ID do co-orientador4; Lattes do co-orientador4; Orientador1; https://orcid.org/; http://lattes.cnpq.br/; Orientador2; https://orcid.org/; http://lattes.cnpq.br/; https://orcid.org/; http://lattes.cnpq.br/; 1º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 2º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 3º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 4º membro da banca; http://lattes.cnpq.br/; 5º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 6º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 7º membro da banca; https://orcid.org/; http://lattes.cnpq.br/
    All-electron basis sets of quintuple and sextuple zeta valence qualities plus polarization functions (5ZP and 6ZP) for the elements from H to Ar, to be used together with the zero-order regular approximation (ZORA), have been developed. To describe electrons distant from the nuclei, diffuse functions were added to the 6ZP non-relativistic set, giving rise to the set designated as augmented 6ZP (A6ZP). A5ZP-ZORA, A6ZP-ZORA, and A6ZP-DKH (Douglas–Kroll–Hess) basis set were also generated. In order to have a better description of some molecular properties, 𝑑-functions with high exponents were added to the ZORA basis sets for the elements of the second-row. Using these basis sets together with the Coupled-Cluster method, ionization energies and static mean dipole polarizabilities of some atoms and geometric parameters, harmonic vibrational frequencies, atomization energies, and electric dipole moments of a set of molecules were calculated and compared with recommended and experimental values found in the literature. The performances of the ZORA and DKH Hamiltonians were evaluated.All-electron basis sets of quintuple and sextuple zeta valence qualities plus polarization functions (5ZP and 6ZP) for the elements from H to Ar, to be used together with the zero-order regular approximation (ZORA), have been developed. To describe electrons distant from the nuclei, diffuse functions were added to the 6ZP non-relativistic set, giving rise to the set designated as augmented 6ZP (A6ZP). A5ZP-ZORA, A6ZP-ZORA, and A6ZP-DKH (Douglas–Kroll–Hess) basis set were also generated. In order to have a better description of some molecular properties, 𝑑-functions with high exponents were added to the ZORA basis sets for the elements of the second-row. Using these basis sets together with the Coupled-Cluster method, ionization energies and static mean dipole polarizabilities of some atoms and geometric parameters, harmonic vibrational frequencies, atomization energies, and electric dipole moments of a set of molecules were calculated and compared with recommended and experimental values found in the literature. The performances of the ZORA and DKH Hamiltonians were evaluated
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    Estrutura eletrônica de sistemas triangulares de carbono e nitreto de boro
    (Universidade Federal do Espírito Santo, 2024-06-03) Terroso, Carolina Jordoni; Co-orientador1; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador2; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador3; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador4; ID do co-orientador4; Lattes do co-orientador4; Pansini, Fernando Néspoli Nassar ; https://orcid.org/0000-0001-8984-686X; http://lattes.cnpq.br/7331959117489023; Orientador2; https://orcid.org/; http://lattes.cnpq.br/; https://orcid.org/0000-0003-0856-5471; http://lattes.cnpq.br/6973934643706120; Souza, Fábio Arthur Leão de ; https://orcid.org/0000-0002-6158-7330; http://lattes.cnpq.br/1140962711692698; Scopel, Wanderlã Luis ; https://orcid.org/0000-0002-2091-8121; http://lattes.cnpq.br/1465127043013658; 3º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 4º membro da banca; http://lattes.cnpq.br/; 5º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 6º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 7º membro da banca; https://orcid.org/; http://lattes.cnpq.br/
    Triangular carbon systems in single monolayer, also known as n-triangulenes (where n is the number of carbon rings at the base of the triangle), hold significant potential in nanoelectronics and spintronics applications due to their electronic structure and ground state multiplicity being dependent on the system’s size. However, controlling their high chemical reactivity at the edges, due to its zig-zag edge configuration, remains a challenge from an experimental standpoint. The strategy investigated in this study to address this characteristic is to create an insulating matrix of hexagonal boron nitride (h-BN) so that the triangulenes can be embedded in the h-BN structure, maintaining their electronic and magnetic properties. Given the size of the studied systems, the Density Functional Theory will be used in all electronic structure calculations. The results revealed that the formation of h-BN or carbon domains is equally possible, and the multiplicities of the ground state are determined solely by the carbon sites, regardless of their position, size, or whether the carbon islands are connected or not. Additionally, Lieb’s Theorem holds true in all cases when considering only the carbon sites, which can be a useful tool in determining the ground state spin of these systems
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    Evolução da rotação de anãs brancas rápidas e magnéticas remanescentes de fusões de binárias de anãs brancas
    (Universidade Federal do Espírito Santo, 2024-08-26) Lacerda, Isabelle Assis; Sousa, Manoel Felipe ; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador2; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador3; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador4; ID do co-orientador4; Lattes do co-orientador4; Coelho, Jaziel Goulart ; https://orcid.org/; http://lattes.cnpq.br/; Orientador2; https://orcid.org/; http://lattes.cnpq.br/; https://orcid.org/; http://lattes.cnpq.br/; Lenzi, César Henrique; https://orcid.org/; http://lattes.cnpq.br/; Rodrigues, Davi Cabral; https://orcid.org/; http://lattes.cnpq.br/; 3º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 4º membro da banca; http://lattes.cnpq.br/; 5º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 6º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 7º membro da banca; https://orcid.org/; http://lattes.cnpq.br/
    Within the population of white dwarfs, there is a group with unusual characteristics that challenge the single-star evolution model to explain their origin. These white dwarfs are massive, highly magnetic, and rapidly rotating, with masses that approach the Chan-drasekhar limit, magnetic field strengths between 106 G and 109 G and rotation periods ranging from minutes to seconds. One proposed formation process for these objects is the coalescence of a binary white dwarf system, where the conservation of mass, angular momentum, and magnetic flux can account for their particular parameters. This thesis studies the rotational evolution of the rapidly rotating, massive, and magnetic white dwarf RE J0317-853 (EUVE J0317-85.5), based on the assumption that it originated from the merger of a double degenerate system. For our investigation, we adopted the modeling developed by Sousa et al. (2022). In the post-merger context, the white dwarf is surrounded by a debris disk, with the presence of a matter flow towards the star. We calculated that the rotation of the white dwarf goes through three distinct phases, linked to the torques acting on it, spending most of its life undergoing magnetic braking. For an accretion rate of M˙ = 1.13 × 10−7 M⊙/year and a disk mass of Md = 0.31 M⊙, RE J0317-853 can reach the observed period of 725.7 s in approximately 0.2 Gyr. We estimated two possible configurations for the progenitor system of this white dwarf based on the mass ratio between the progenitors. RE J0317-853 could be the product of the merger of a white dwarf system with masses of 1.00 M⊙ and 0.50 M⊙, or it could have been formed by the coalescence of progenitors with masses of 0.75 M⊙ and 0.74 M⊙. The results obtained in this study resemble those of Sousa et al. (2022) for the progenitors of the white dwarf J2211+1136 (0,98 M⊙ and 0,49 M⊙), which, in turn, are similar to the configuration of the known double degenerate system NLTT 12758 (0,83 M⊙ and 0,69 M⊙), studied by Kawka et al. (2016). Another binary system composed of white dwarfs with masses similar to our estimates is the system NLTT 44447, formed by the magnetic white dwarf with 0.94 M⊙ and its non-magnetic companion, with 0.54 M⊙ (KAWKA et al., 2016). However, this system lacks measurements of the orbital period and rotational period of the stars. Future measurements of these parameters would allow a better assessment of the similarity between our estimate and this system, indicating whether this binary system could undergo coalescence
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    Intercalação de lítio na heteroestrutura Janus WSSe/Siliceno
    (Universidade Federal do Espírito Santo, 2024-02-06) Cintra, Gabriel Borelli; Co-orientador1; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador2; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador3; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador4; ID do co-orientador4; Lattes do co-orientador4; Orientador1; https://orcid.org/; http://lattes.cnpq.br/; Orientador2; https://orcid.org/; http://lattes.cnpq.br/; https://orcid.org/; http://lattes.cnpq.br/; 1º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 2º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 3º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 4º membro da banca; http://lattes.cnpq.br/; 5º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 6º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 7º membro da banca; https://orcid.org/; http://lattes.cnpq.br/
    In this dissertation, a theoretical study is presented through computer simulations based on the density functional theory (DFT) to investigate the electronic and structural properties of the WSSe/Silicene heterostructure and its applicability as an electrode for a lithium ion battery. To achieve this, the lithium interaction with each monolayer was examined, indicating a symbiotic relationship in the formation of the heterostructure, resulting in electronic and structural characteristics conducive to energy storage. The conducted calculations reveal that (1) the formation of the heterostructure is an exothermic process, yielding a conductive material, (2) lithium adsorption is energetically favorable with binding energies on the order of 3.0 eV for the heterostructure, exhibiting a metallic character in the obtained structure, (3) the energy barrier for ion diffusion is on the order of 0.34 eV, (4) the open-circuit voltage measured with ion concentration variation ranged from 1.29 to 1.02 V, decreasing with increasing concentration. Based on the obtained results, the studied heterostructure possesses suitable characteristics for an anode material