Analytical differentiation of the energy contribution due to triple excitations in quadratic configuration interaction theory

✍ Scribed by Jürgen Gauss; Dieter Cremer

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 420 KB
• Volume: 163
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(89)85185-1

✦ Synopsis

Formulae for the analytical differentiation of the energy contribution due to triple excitations (T) within quadratic conftguration interaction (QCI) theory are derived. Combining these formulae with previously derived formulae for the evaluation of analytical first derivatives for QCI theory with single (S) and double excitations (D), au algorithm is developed to calculate analytical QCISD (T) energy gradients. The applicability of this algorithm is demonstrated by calculating the equilibrium geometry ofCH,OO at the QCISD(T)/631G(d, p) level oftheory.