Biorthogonal approach for explicitly correlated calculations using the transcorrelated Hamiltonian

A biorthogonal formulation is applied to the non-Hermite transcorrelated Ha miltonian, which treats a large amount of the dynamic correlation effects i mplicitly. We introduce biorthogonal canonical orbitals diagonalizing the n on-Hermitian Fock operator. We also formulate many-body perturbation theory for the transcorrelated Hamiltonian. The biorthogonal self-consistent fiel d followed by the second order perturbation theory are applied to some pilo t calculations including small atoms and molecules. (C) 2001 American Insti tute of Physics.