Abstract
The projected unrestricted coupled cluster wave function with singly and doubly excited clusters (PUCCSD) has been used as a source of information about the T3 and T4 cluster contributions in the externally corrected CCSD approach. In order to remove the spin contamination of the UCCSD wave function the group invariant average of the unitary group was adapted. Preliminary results presented here for the DZ H8 model system show surprisingly good agreement with the exact results, particularly in the case of the energy contribution of the T4 cluster to the quasidegenerate region with errors of less than 0.1milihartree.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
