  New algebraic structure on electronic Fock space is studied in detail. This
structure is defined in terms of a certain multiplication of many electron wave
functions and has close interrelation with coupled cluster and similar
approaches. Its study clarifies and simplifies the mathematical backgrounds of
these approaches. And even more, it leads to many relations that would be very
difficult to derive using conventional technique. Formulas for action of the
creation-annihilation operators on products of state vectors are derived.
Explicit expressions for action of simplest particle-conserving products of the
creation-annihilation operators on powers of state vectors are given. General
scheme of parametrization of representable density operators of arbitrary order
is presented.
