原子力、振动和非谐性的电子量子蒙特卡罗计算
Electronic Quantum Monte Carlo Calculations of Atomic Forces, Vibrations, and Anharmonicities
摘要：
用电子量子蒙特卡罗方法计算了第一排单晶和一氧化碳的原子力。通过改进变分QMC中变分参数的移动方法，获得了精确有效的力。在初始SD步骤之后，将具有奇异值分解（SVD）的牛顿方法与沿着SVD拒绝的方向的最速下降（SD）更新相结合。在变分和扩散QMC中的离解能与实验符合得很好。原子力与势能面在数量上一致，证明了这种力过程的准确性。由QMC能量和原子力导出的简谐振动频率和非简谐常数也与实验值吻合得很好。
英文摘要：
Atomic forces are calculated for first-row monohydrides and carbon monoxide within electronic quantum Monte Carlo (QMC). Accurate and efficient forces are achieved by using an improved method for moving variational parameters in variational QMC. Newton's method with singular value decomposition (SVD) is combined with steepest descent (SD) updates along directions rejected by the SVD, after initial SD steps. Dissociation energies in variational and diffusion QMC agree well with experiment. The atomic forces agree quantitatively with potential energy surfaces, demonstrating the accuracy of this force procedure. The harmonic vibrational frequencies and anharmonicity constants, derived from the QMC energies and atomic forces, also agree well with experimental values.
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