A complex scaled multiconfigurational time-dependent Hartree–Fock method for studying resonant states

Abstract

A new complex scaled multiconfigurational time-dependent Hartree–Fock (CMCTDHF) method (also called the complex scaled multiconfigurational linear response (CMCLR)) has been developed. CMCTDHF uses complex multiconfigurational Hartree–Fock states as initial states, and in real space has been successfully used to study electronic excitation energies and linear response properties. With CMCTDHF, shape and Feshbach resonances of an N-electron system can be obtained by studying the excited states of an (N + 1)-electron system with the trajectory method. Our first application of CMCTDHF has been for the beryllium doubly excited state 1Po (1s2 2p 3s) with a 14s 14p 5d Gaussian basis and a 2s 2p 3s 3p 3d complete active space (CAS). We find the resonance position and width are (11.01, 0.434) eV, which agrees very well with the experimental result (10.89, 0.531) eV. This is the first time that the complex scaling method has been successfully used to study beryllium doubly excited states. Our calculations show that CMCTDHF is a practical and important tool for studying resonant states.