Investigation of electron–hole correlation using explicitly correlated configuration interaction method

The explicitly correlated configuration interaction (XCCI) method is presented as a general technique for accurate description of electron–hole interaction. The XCCI method is a variational method where an R12-explicitly correlated wavefunction that depends on the electron–hole separation is used as the zeroth order reference wavefunction for performing the CI expansion. This is the main feature that differentiates the XCCI from the conventional CI method. Benchmark calculations on parabolic quantum dot using XCCI, FCI, and R12-FCI methods are presented and the results demonstrate that XCCI wavefunction is variationally superior to the FCI wavefunction for the ground and the excited states.