Revisitation of Nonorthogonal Spin Adaptation in Coupled Cluster Theory

详细信息    查看全文

• 作者：Devin A. Matthews ; J眉rgen Gauss ; John F. Stanton
• 刊名：Journal of Chemical Theory and Computation
• 出版年：2013
• 出版时间：June 11, 2013
• 年：2013
• 卷：9
• 期：6
• 页码：2567-2572
• 全文大小：254K
• 年卷期：v.9,no.6(June 11, 2013)
• ISSN：1549-9626

文摘

The benefits of what is alternatively called a nonorthogonally spin-adapted, spin-free, or orbital representation of the coupled cluster equations is discussed relative to orthogonally spin-adapted, spin鈥搊rbital, and spin-integrated theories. In particular, specific linear combinations of the orbital cluster amplitudes, denoted spin-summed amplitudes, are shown to reduce the number of contractions that must be explicitly performed and to simplify the expressions and their derivation. The computational efficiency of the spin-summed approach is discussed and compared to orthogonally spin-adapted and spin-integrated approaches. The spin-summed approach is shown to have significant computational advantages relative to the other methods for CCSDT and CCSDTQ.