Bases gaussianas geradas com os métodos Monte Carlo Simulated Annealing e Particle Swarm Optimization.

• Autor(a) principal: Reis, Thiago Mello dos
• Data de Publicação: 2017
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/7378
• topic: Bases Gaussianas; Método Monte Carlo; Átomos; Física; 53

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