Coupled-cluster methods correct through sixth order

✍ Scribed by Stanislaw A. Kucharski; Rodney J. Bartlett

• Book ID: 103035797
• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 819 KB
• Volume: 206
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(93)80186-s

✦ Synopsis

Several coupled-cluster approximations to the full CCSDTQ model, correct through sixth order, are presented and illustrated by numerical comparisons to full CI. Both iterative and non-iterative methods built upon underlying CCSDT solutions are considered. Unlike CCSDTQ, which is an -n" computational procedure, the computational dependence of all approximations is no worse than -n9. The latter follows from use of the 2n rule of perturbation theory. The average errors compared to full CI for different methods are 0.1 to 0.3 mhartree, compared to 0.05 mhartree for CCSDTQ.