Guidelines on the Contracted Schrödinger Equation Methodology

Abstract

In this article the aim is to provide a guide to the Contracted Schrödinger Equation (CSE) methodology for those readers who are not yet familiar with it. Therefore, the accent is put on giving a clear outlook of the two methods which are now being sucessfully applied: The iterative solution of the second-order CSE and the variational and also iterative solution of the second-order hypervirial equation which can be identified with the continuity equation, or contracted Liouville equation, and with the Antihermitian form of the 2-CSE (2-ACSE). This is not, therefore, a proper revision of the subject but an introduction to an accurate and competitive ab-initio methodology for the study of atoms, molecules and clusters. The results obtained when applying both these methods to the study of the BeH₂ and Li₂ molecules are also given here.