CI algorithms in ab initio code
Speaker: Roland Lindh
Affiliation: Uppsala University
Type: Contributed talk
Abstract
The presentation deals with the implementation of a new library of CI algorithms. Here adapted to the OpenMOLCAS open-source codes. This introduces the Algebraic Spin-Tensor Approach, ASTA, as implemented in the Split-Graph UGA formalism of Malmquist in the basis of Configuration State Functions, CSFs. This has been co-developed with the Slater-Determinant code of Vacoille – the Faroald routines. The target is to develop general stand-alone codes for the underlying CI algorithms of methods as CASSCF, RASSCF, GASSCF, LASSCF, and all forms of selected CI approaches. The presentation will reflect on the various considerations a reusable library have to address in order to be a general tool applicable to multiconfigurational methods in general.
The presentation will also present how the use of a minimal entropy approach will allow for the possibly most compact representation of the Full CI wave function – using the orbital invariance to get the most compact representation of the multiconfigurational wave function.