Max-Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany.
Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Gothenburg, Sweden.
J Chem Phys. 2023 Jun 14;158(22). doi: 10.1063/5.0147877.
We investigate the optimization of flexible tailored real-space Jastrow factors for use in the transcorrelated (TC) method in combination with highly accurate quantum chemistry methods, such as initiator full configuration interaction quantum Monte Carlo (FCIQMC). Jastrow factors obtained by minimizing the variance of the TC reference energy are found to yield better, more consistent results than those obtained by minimizing the variational energy. We compute all-electron atomization energies for the challenging first-row molecules C2, CN, N2, and O2 and find that the TC method yields chemically accurate results using only the cc-pVTZ basis set, roughly matching the accuracy of non-TC calculations with the much larger cc-pV5Z basis set. We also investigate an approximation in which pure three-body excitations are neglected from the TC-FCIQMC dynamics, saving storage and computational costs, and show that it affects relative energies negligibly. Our results demonstrate that the combination of tailored real-space Jastrow factors with the multi-configurational TC-FCIQMC method provides a route to obtaining chemical accuracy using modest basis sets, obviating the need for basis-set extrapolation and composite techniques.
我们研究了灵活定制实空间 Jastrow 因子的优化，以用于与高精度量子化学方法（如引发剂全组态相互作用量子蒙特卡罗（FCIQMC））相结合的交联（TC）方法。通过最小化 TC 参考能量的方差获得的 Jastrow 因子比通过最小化变分能量获得的因子具有更好、更一致的结果。我们计算了具有挑战性的第一行分子 C2、CN、N2 和 O2 的全电子原子化能，发现仅使用 cc-pVTZ 基组，TC 方法即可得到化学准确的结果，与使用更大的 cc-pV5Z 基组的非 TC 计算的准确性大致匹配。我们还研究了一种近似方法，其中从 TC-FCIQMC 动力学中忽略了纯三体激发，从而节省了存储和计算成本，并表明它对相对能量的影响可以忽略不计。我们的结果表明，定制实空间 Jastrow 因子与多组态 TC-FCIQMC 方法的结合为使用适度的基组获得化学准确性提供了一种途径，避免了基组外推和组合技术的需要。
