Zundel离子的全量子描述：变分量子Monte Carlo与路径积分Langevin动力学的结合
Fully quantum description of the Zundel ion: combining variational quantum Monte Carlo with path integral Langevin dynamics
摘要：
介绍了一种从第一性原理出发对电子-离子耦合系统进行全量子描述的新方法。它结合了电子部分的变分量子蒙特卡罗（QMC）解和量子核动力学的路径积分（PI）形式。一方面，PI分子动力学包括核量子效应，通过添加一组虚构的经典粒子（珠），旨在通过谐波动力学项再现核量子涨落。另一方面，变分QMC可以提供Born-Oppenheimer（BO）势能面的精度相媲美的最先进的后Hartree-Fock方法，并具有良好的缩放与系统的大小。为了处理QMC的固有噪声，我们根据QMC核力的协方差矩阵，用一个相关的Langevin恒温器对PI分子动力学进行了推广。QMC波函数的变分参数在核动力学过程中演化，使得BO势能面无偏。通过采用珠粒分组平均法，减少了波函数参数的统计误差。我们的一般算法依赖于由离子力驱动的动力学和由谐波interbead耦合的一组之间的特罗特分手。后者是完全集成，即使在朗之万恒温器的存在下，由于映射到一个奥恩斯坦-乌伦贝克过程。这个框架在确定性离子力的情况下也是非常有效的。新的实现验证Zundel离子通过直接比较与标准PI Langevin动力学计算与耦合集群势能面。核量子效应被证实是占主导地位的热效应远远超过室温，使多余的质子增加流动性的量子隧穿。
英文摘要：
We introduce a novel approach for a fully quantum description of coupled electron-ion systems from first principles. It combines the variational quantum Monte Carlo (QMC) solution of the electronic part with the path integral (PI) formalism for the quantum nuclear dynamics. On the one hand, the PI molecular dynamics includes nuclear quantum effects by adding a set of fictitious classical particles (beads) aimed at reproducing nuclear quantum fluctuations via a harmonic kinetic term. On the other hand, variational QMC can provide Born-Oppenheimer (BO) potential energy surfaces with a precision comparable to the most advanced post Hartree-Fock approaches, and with a favorable scaling with the system size. To deal with the intrinsic QMC noise, we generalize the PI molecular dynamics using a Langevin thermostat correlated according to the covariance matrix of QMC nuclear forces. The variational parameters of the QMC wave function are evolved during the nuclear dynamics, such that the BO potential energy surface is unbiased. Statistical errors on the wave function parameters are reduced by resorting to bead grouping average, which we show to be accurate and well controlled. Our general algorithm relies on a Trotter breakup between the dynamics driven by ionic forces and the one set by the harmonic interbead couplings. The latter is exactly integrated even in presence of the Langevin thermostat, thanks to the mapping onto an Ornstein-Uhlenbeck process. This framework turns out to be very efficient also in the case of deterministic ionic forces. The new implementation is validated on the Zundel ion by direct comparison with standard PI Langevin dynamics calculations made with a coupled cluster potential energy surface. Nuclear quantum effects are confirmed to be dominant over thermal effects well beyond room temperature giving the excess proton an increased mobility by quantum tunneling.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
