A quantum algorithm for spin chemistry: a Bayesian exchange coupling parameter calculator with broken-symmetry wave functions.
Kenji SugisakiKazuo ToyotaKazunobu SatoDaisuke ShiomiTakeji TakuiPublished in: Chemical science (2020)
The Heisenberg exchange coupling parameter J (H = -2J S i · S j ) characterises the isotropic magnetic interaction between unpaired electrons, and it is one of the most important spin Hamiltonian parameters of multi-spin open shell systems. The J value is related to the energy difference between high-spin and low-spin states, and thus computing the energies of individual spin states are necessary to obtain the J values from quantum chemical calculations. Here, we propose a quantum algorithm, B̲ayesian ex̲change coupling parameter calculator with b̲roken-symmetry wave functions (BxB), which is capable of computing the J value directly, without calculating the energies of individual spin states. The BxB algorithm is composed of the quantum simulations of the time evolution of a broken-symmetry wave function under the Hamiltonian with an additional term j S 2, the wave function overlap estimation with the SWAP test, and Bayesian optimisation of the parameter j. Numerical quantum circuit simulations for H2 under a covalent bond dissociation, C, O, Si, NH, OH+, CH2, NF, O2, and triple bond dissociated N2 molecule revealed that the BxB can compute the J value within 1 kcal mol-1 of errors with less computational costs than conventional quantum phase estimation-based approaches.
Keyphrases
- molecular dynamics
- density functional theory
- room temperature
- monte carlo
- machine learning
- ionic liquid
- deep learning
- transition metal
- single molecule
- signaling pathway
- energy transfer
- immune response
- preterm infants
- lps induced
- electron transfer
- toll like receptor
- minimally invasive
- single cell
- molecular dynamics simulations
- molecularly imprinted
- mass spectrometry
- preterm birth
- quality improvement
- adverse drug
- nuclear factor
- gestational age