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DOE OSTI · 1803729

A Multireference Quantum Krylov Algorithm for Strongly Correlated Electrons

Stair, Nicholas H.·Huang, Renke·Evangelista, Francesco A.
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Abstract

We introduce a multireference selected quantum Krylov (MRSQK) algorithm suitable for quantum simulation of many-body problems. MRSQK is a low-cost alternative to the quantum phase estimation algorithm that generates a target state as a linear combination of non-orthogonal Krylov basis states. This basis is constructed from a set of reference states via real-time evolution; thus, avoiding the numerical optimization of parameters. An efficient algorithm for the evaluation of the off-diagonal matrix elements of the overlap and Hamiltonian matrices is discussed and a selection procedure is introduced to identify a basis of orthogonal references that ameliorates the linear dependency problem. Preliminary benchmarks on linear H 6 , H 8 , and BeH 2 indicate that MRSQK can predict the energy of these systems accurately using very compact Krylov bases.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRYHamiltoniansalgorithmscircuitsdeterminantsmathematical methods

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Stair, Nicholas H., Huang, Renke, Evangelista, Francesco A.. 2020-02-24. A Multireference Quantum Krylov Algorithm for Strongly Correlated Electrons. https://doi.org/10.1021/acs.jctc.9b01125

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