COMPACT CONFIGURATION INTERACTION WAVE FUNCTIONS: HYBRID EXCITATION-LEVEL AND SENIORITY-NUMBER APPROACHES

OFELIA B. OÑA; DIEGO R. ALCOBA; ALICIA TORRE; LUIS LAIN; G. E. MASSACCESI; P. CAPUZZI; MARIO VAN RAEMDONCK; PATRICK BULTINCK; DIMITRI VAN NECK

La Plata

Seminario; SEMINARIOS DE LA DIVISION QUIMICA-TEORICA; 2015

INIFTA, CONSEJO NACIONAL DE INVESTIGACIONES CIENTIFICAS Y TECNICAS

The Full Configuration Interaction (FCI) wave functions, usually expressed in terms of N-electron Slater determinants, constitute the exact solutions of the Schrödinger equation of an N-electron system for a given one-electron basis set. However, they render prohibitive computational costs, except for systems having a low number of electrons described by small size basis sets. Consequently, the overcoming of this drawback requires the search of approximated methods. In this presentation we examine different Configuration Interaction (CI) truncation strategies to generate compact wave functions. We focus on the performance of CI methods in which the Hamiltonian of an N-electron system is projected on Slater determinants selected according to the traditional excitation-level procedure and the concept of seniority number of a determinant [1-4]. The compactness and configurational structure of the resulting N-electron wave functions expressed in several types of molecular orbital basis sets are assessed by means of numerical determinations of entropic indices formulated within the Information Theory framework.