Reduced scaling extended multi-state CASPT2 (XMS-CASPT2) using supporting subspaces and tensor hyper-contraction

Song, Chenchen; Martínez, Todd J.

doi:10.1063/5.0007417

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Reduced scaling extended multi-state CASPT2 (XMS-CASPT2) using supporting subspaces and tensor hyper-contraction

Song, Chenchen·Martínez, Todd J.

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Abstract

We present a reduced scaling formulation of the extended multi-state CASPT2 (XMS-CASPT2) method, which is based on our recently developed state-specific CASPT2 (SS-CASPT2) formulation using supporting subspaces and tensor hyper-contraction. By using these two techniques, the off-diagonal elements of the effective Hamiltonian can be computed with only O(N 3 ) operations and O(N 2 ) memory, where N is the number of basis functions. Furthermore, this limits the overall computational scaling to O(N 4 ) operations and O(N 2 ) memory. Thus, excited states can now be obtained at the same reduced (relative to previous algorithms) scaling we achieved for SS-CASPT2.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY Complete-active space self-consistent field Correlation-consistent basis sets Excitation energies Excited state energies Fock operator Graphics processing units Perturbation theory Potential energy surfaces Proteins Quantum mechanical/molecular mechanical calculations

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Song, Chenchen, Martínez, Todd J.. 2020-06-17. Reduced scaling extended multi-state CASPT2 (XMS-CASPT2) using supporting subspaces and tensor hyper-contraction. https://doi.org/10.1063/5.0007417

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