用扩散量子蒙特卡罗方法计算线性和非线性磁化率：对周期性氢链的应用
Linear and Non-linear Susceptibilities from Diffusion Quantum Monte Carlo: Application to Periodic Hydrogen Chains
摘要：
我们用扩散量子蒙特卡罗方法计算了不同键长交替的氢二聚体周期性纵向链的线性和非线性极化率。这些数量来自于电子极化的变化作为施加有限电场的函数-我们最近引入的一种方法，并通过使用贝里相，多体电焓功能成为可能。计算的亲油度和超亲油度被认为是在极好的协议与最好的估计，可从量子化学-通常外推到无限链的限制计算有限长度的链。结果发现，虽然交换效应占主导地位的适当的描述的磁化率，第二超磁化率的电子关联的影响很大。我们还评估了如何不同的近似节点表面的多体波函数影响的准确性计算的可压缩性。
英文摘要：
We calculate the linear and non-linear susceptibilities of periodic longitudinal chains of hydrogen dimers with different bond-length alternations using a diffusion quantum Monte Carlo approach. These quantities are derived from the changes in electronic polarization as a function of applied finite electric field - an approach we recently introduced and made possible by the use of a Berry-phase, many-body electric-enthalpy functional. Calculated susceptibilities and hyper-susceptibilities are found to be in excellent agreement with the best estimates available from quantum chemistry - usually extrapolations to the infinite-chain limit of calculations for chains of finite length. It is found that while exchange effects dominate the proper description of the susceptibilities, second hyper-susceptibilities are greatly affected by electronic correlations. We also assess how different approximations to the nodal surface of the many-body wavefunction affect the accuracy of the calculated susceptibilities.
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