Nuclear Ensemble Approach with Importance Sampling

Autor(es)

Kossoski, Fabris ^{[1, 2]} ; Barbatti, Mario ^[2]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Inst Fis Gleb Wataghin, BR-13083859 Campinas, SP - Brazil

^[2] Aix Marseille Univ, ICR, CNRS, Marseille - France

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF CHEMICAL THEORY AND COMPUTATION; v. 14, n. 6, p. 3173-3183, JUN 2018.
• Citações Web of Science: 5

Resumo

We show that the importance sampling technique can effectively augment the range of problems where the nuclear ensemble approach can be applied. A sampling probability distribution function initially determines the collection of initial conditions for which calculations are performed, as usual. Then, results for a distinct target distribution are computed by introducing compensating importance sampling weights for each sampled point. This mapping between the two probability distributions can be performed whenever they are both explicitly constructed. Perhaps most notably, this procedure allows for the computation of temperature dependent observables. As a test case, we investigated the UV absorption spectra of phenol, which has been shown to have a marked temperature dependence. Application of the proposed technique to a range that covers 500 K provides results that converge to those obtained with conventional sampling. We further show that an overall improved rate of convergence is obtained when sampling is performed at intermediate temperatures. The comparison between calculated and the available measured cross sections is very satisfactory, as the main features of the spectra are correctly reproduced. As a second test case, one of Tully's classical models was revisited, and we show that the computation of dynamical observables also profits from the importance sampling technique. In summary, the strategy developed here can be employed to assess the role of temperature for any property calculated within the nuclear ensemble method, with the same computational cost as doing so for a single temperature. (AU)

• Processo FAPESP: 16/21880-7 - Implementação de tempos de vida finitos de ânions transientes em simulações de dinâmica semiclássica
• Beneficiário: Fábris Kossoski
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado