TY - JOUR

T1 - Electric Field Gradient Calculations for Ice VIII and IX Using Polarizable Embedding

T2 - A Comparative Study on Classical Computers and Quantum Simulators

AU - Nagy, Dániel

AU - Reinholdt, Peter

AU - Jensen, Phillip W.K.

AU - Kjellgren, Erik Rosendahl

AU - Ziems, Karl Michael

AU - Fitzpatrick, Aaron

AU - Knecht, Stefan

AU - Kongsted, Jacob

AU - Coriani, Sonia

AU - Sauer, Stephan P.A.

PY - 2024/7/17

Y1 - 2024/7/17

N2 - We test the performance of the polarizable embedding variational quantum eigensolver self-consistent field (PE-VQE-SCF) model for computing electric field gradients with comparisons to conventional complete active space self-consistent-field (CASSCF) calculations and experimental results. We compute quadrupole coupling constants for ice VIII and ice IX. We find close agreement of the quantum-computing PE-VQE-SCF results with the results from the classical PE-CASSCF calculations and with experiment. Furthermore, we observe that the inclusion of the environment is crucial for obtaining results that match the experimental data. The calculations for ice VIII are within the experimental uncertainty for both CASSCF and VQE-SCF for oxygen and lie close to the experimental value for ice IX as well. With the VQE-SCF, which is based on an adaptive derivative-assembled problem-tailored (ADAPT) ansatz, we find that the inclusion of the environment and the size of the different basis sets do not directly affect the gate counts. However, by including an explicit environment, the wavefunction and therefore the optimization problem become more complicated, which usually results in the need to include more operators from the operator pool, thereby increasing the depth of the circuit.

AB - We test the performance of the polarizable embedding variational quantum eigensolver self-consistent field (PE-VQE-SCF) model for computing electric field gradients with comparisons to conventional complete active space self-consistent-field (CASSCF) calculations and experimental results. We compute quadrupole coupling constants for ice VIII and ice IX. We find close agreement of the quantum-computing PE-VQE-SCF results with the results from the classical PE-CASSCF calculations and with experiment. Furthermore, we observe that the inclusion of the environment is crucial for obtaining results that match the experimental data. The calculations for ice VIII are within the experimental uncertainty for both CASSCF and VQE-SCF for oxygen and lie close to the experimental value for ice IX as well. With the VQE-SCF, which is based on an adaptive derivative-assembled problem-tailored (ADAPT) ansatz, we find that the inclusion of the environment and the size of the different basis sets do not directly affect the gate counts. However, by including an explicit environment, the wavefunction and therefore the optimization problem become more complicated, which usually results in the need to include more operators from the operator pool, thereby increasing the depth of the circuit.

U2 - 10.1021/acs.jpca.4c02697

DO - 10.1021/acs.jpca.4c02697

M3 - Journal article

C2 - 39020525

AN - SCOPUS:85198965686

SN - 1089-5639

VL - 128

SP - 6305

EP - 6315

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

IS - 30

ER -