We present a new local multi-reference singles and doubles configuration interaction (MRSDCI) algorithm. The method presented here eliminates configurations if they involve simultaneous excitations out of widely separated internal orbitals and is therefore based on the weak pairs approximation of Saebø and Pulay. Although the resulting truncated CI expansions have only about 50% as many CSFs as the non-local MRSDCI, we show that they can recover over 99% of the correlation energy. Additionally, we show for the first time that they can accurately describe bond dissociation.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry