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arXiv · 1501.02780

Automatic code generation enables nuclear gradient computations for fully internally contracted multireference theory

Matthew K. MacLeod·Toru Shiozaki
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Abstract

Analytical nuclear gradients for fully internally contracted complete active space second-order perturbation theory (CASPT2) are reported. This implementation has been realized by an automated code generator that can handle spin-free formulas for the CASPT2 energy and its derivatives with respect to variations of molecular orbitals and reference coefficients. The underlying complete active space self-consistent field and the so-called Z-vector equations are solved using density fitting. The implementation has been applied to the vertical and adiabatic ionization potentials of the porphin molecule to illustrate its capability.

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Matthew K. MacLeod, Toru Shiozaki. 2015-01-26. Automatic code generation enables nuclear gradient computations for fully internally contracted multireference theory. https://doi.org/10.1063/1.4907717

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