A derivation of the frozen-orbital unrestricted open-shell and restricted closed-shell second-order perturbation theory analytic gradient expressions
Webb, Simon P.
Bell, Rob L.
Fletcher, Graham D.
Schmidt, Michael W.
Gordon, Mark S.
Is Version Of
ChemistryAmes National Laboratory
A detailed derivation of the frozen-orbital second-order perturbation theory (MP2) analytic gradient in the spin-orbital basis is presented. The summation ranges and modification of the MP2 gradient terms that result from the frozen-orbital approximation are clearly identified. The frozen-orbital analytic gradients for unrestricted MP2 and closed-shell MP2 are determined from the spin-orbital derivation. A discussion of useful implementation procedures is included. Timings from full and frozen-orbital MP2 gradient calculations on the molecule silicocene (the silicon analog of the sandwich compound ferrocene) are also presented.
This article is published as Aikens, Christine M., Simon P. Webb, Rob L. Bell, Graham D. Fletcher, Michael W. Schmidt, and Mark S. Gordon. "A derivation of the frozen-orbital unrestricted open-shell and restricted closed-shell second-order perturbation theory analytic gradient expressions." Theoretical Chemistry Accounts 110, no. 4 (2003): 233-253. DOI: 10.1007/s00214-003-0453-3. Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.