A time-dependent formulation of multi-reference perturbation theory
We discuss the time-dependent formulation of perturbation theory in the context of the interacting zeroth-order Hamiltonians that appear in multi-reference situations. As an example, we present a time-dependent formulation and implementation of second-order n-electron valence perturbation theory. The resulting time-dependent n-electron valence second-order perturbation theory (t-NEVPT2) method yields the fully uncontracted n-electron valence perturbation wavefunction and energy, but has a lower computational scaling than the usual contracted variants, and also avoids the construction of high-order density matrices and the diagonalization of metrics. We present results of t-NEVPT2 for the water, nitrogen, carbon, and chromium molecules and outline directions for the future.
© 2016 AIP Publishing LLC. Received 30 December 2015; accepted 28 January 2016; published online 10 February 2016. This work was supported by the U.S. Department of Energy, Office of Science through Award No. DE-SC0008624 (primary support for A.Y.S.), and Award No. DE-SC0010530 (additional support for G.K.-L.C.). A.Y.S. would like to thank Dr. Qiming Sun, Dr. Enrico Ronca, and Sheng Guo for insightful discussions.
Published - 1_2E4941606.pdf
Accepted Version - 1512.09213.pdf