Towards the Simulation of Large Scale ProteinLigand Interactions on NISQera Quantum Computers
Abstract
We explore the use of symmetryadapted perturbation theory (SAPT) as a simple and efficient means to compute interaction energies between large molecular systems with a hybrid method combing NISQera quantum and classical computers. From the one and twoparticle reduced density matrices of the monomer wavefunctions obtained by the variational quantum eigensolver (VQE), we compute SAPT contributions to the interaction energy [SAPT(VQE)]. At first order, this energy yields the electrostatic and exchange contributions for noncovalently bound systems. We empirically find from ideal statevector simulations that the SAPT(VQE) interaction energy components display orders of magnitude lower absolute errors than the corresponding VQE total energies. Therefore, even with coarsely optimized lowdepth VQE wavefunctions, we still obtain sub kcal/mol accuracy in the SAPT interaction energies. In SAPT(VQE), the quantum requirements, such as qubit count and circuit depth, are lowered by performing computations on the separate molecular systems. Furthermore, active spaces allow for large systems containing thousands of orbitals to be reduced to a small enough orbital set to perform the quantum portions of the computations. We benchmark SAPT(VQE) (with the VQE component simulated by ideal statevector simulators) against a handful of small multireference dimer systems and the iron center containing human cancerrelevant protein lysinespecific demethylase 5 (KDM5A).
 Publication:

arXiv eprints
 Pub Date:
 October 2021
 DOI:
 10.48550/arXiv.2110.01589
 arXiv:
 arXiv:2110.01589
 Bibcode:
 2021arXiv211001589M
 Keywords:

 Quantum Physics;
 Physics  Chemical Physics
 EPrint:
 16 pages, 4 figures, plus supplemental data