Pure representability problem and new models of the electronic fock space

摘要

New models of the Fock space sector sector corresponding to some fixed number of electrons are introduced.These models originate from the representability theory and their practical implementation may lead to essential reduction of dimensions of intermediate CI soaces.A certain zero-order theory is proposed that gives wavefunctions approximately equivalent to ones obtained by accounting for all excitations from the Hartree-Fock reference state up to the 9th order.Simple numerical examples are given to illustrate our approach.