Analytical nonadiabatic couplings and gradients within the state-averaged orbital-optimized variational quantum eigensolver

Autor: Yalouz, Saad, Koridon, Emiel, Senjean, Bruno, Lasorne, Benjamin, Buda, Francesco, Visscher, Lucas
Rok vydání: 2021
Předmět:
Zdroj: Journal of Chemical Theory and Computation 2022 18 (2), 776-794
Druh dokumentu: Working Paper
DOI: 10.1021/acs.jctc.1c00995
Popis: In this work, we introduce several technical and analytical extensions to our recent state-averaged orbital-optimized variational quantum eigensolver (SA-OO-VQE) algorithm (see Ref. [S. Yalouz et al. ,Quantum Sci. Technol. 6, 024004 (2021).]). Motivated by the limitations of current quantum computers, the first extension consists in an efficient state-resolution procedure to find the SA-OO-VQE eigenstates, and not just the subspace spanned by them, while remaining in the equi-ensemble framework. This approach avoids expensive intermediate resolutions of the eigenstates by postponing this problem to the very end of the full algorithm. The second extension allows for the estimation of analytical gradients and non-adiabatic couplings, which are crucial in many practical situations ranging from the search of conical intersections to the simulation of quantum dynamics, in, for example, photoisomerization reactions. The accuracy of our new implementations is demonstrated on the formaldimine molecule CH$_2$NH (a minimal Schiff base model relevant for the study of photoisomerization in larger bio-molecules), for which we also perform a geometry optimization to locate a conical intersection between the ground and first-excited electronic states of the molecule.
Comment: 22 pages, 7 figures
Databáze: arXiv