arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0806.4169physics.chem-phcond-mat.other
收藏

氢键的量子蒙特卡罗方法

Dissecting the hydrogen bond: a Quantum Monte Carlo approach

Fabio Sterpone, Leonardo Spanu, Luca Ferraro, Sandro Sorella, Leonardo Guidoni

摘要:

我们提出了一个变分蒙特卡罗(VMC)和晶格正则化扩散蒙特卡罗(LRDMC)研究的结合能和色散曲线的水二聚体。作为一种变体,我们使用JAGP波函数,一种共振价键(RVB)思想的实现。实际上,本工作的目的之一是研究如何键合的两个水分子,作为一个原型的氢键复合物,可以描述在一个JAGP方法。使用氧的惰性核的赝势,通过变分参数的完全优化,我们在VMC水平上获得了-4.5(0.1)Kcal/mol的结合能,而LRDMC计算给出了-4.9(0.1)Kcal/mol(实验5 Kcal/Mol)。计算的色散曲线在VMC和LRDMC水平上再现了最小位置和曲率。WF的质量使我们有可能通过适当地关闭JAGP中的行列式和Jastrow项来分解不同贡献的结合能:我们估计动力学对结合能的贡献约为1.4(0.2)Kcal/Mol,而共价贡献约为1.0(0.2)Kcal/Mol。因此,JAGP揭示了一个很有前途的WF描述系统中,分散力和共价力起着重要作用。

英文摘要:

We present a variational MonteCarlo (VMC) and lattice regularized diffusion MonteCarlo (LRDMC) study of the binding energy and dispersion curve of the water dimer. As a variation ansatz we use the JAGP wave function, an implementation of the resonating valence bond (RVB) idea. Actually one the aim of the present work is to investigate how the bonding of two water molecules, as a prototype of the hydrogen-bonded complexes, could be described within an JAGP approach. Using a pseudopotential for the inert core of the Oxygen, with a full optimization of the variational parameters, we obtain at the VMC level a binding energy of -4.5(0.1) Kcal/mol, while LRDMC calculations gives -4.9(0.1) Kcal/mol (experiment 5 Kcal/Mol). The calculated dispersion curve reproduces both at the VMC and LRDMC level the miminum position and the curvature.The quality of the WF gives us the possibility to dissect the binding energy in different contributions by appropriately switching off determinantal and Jastrow terms in the JAGP: we estimate the dynamical contribution to the binding energy to be of the order of 1.4(0.2) Kcal/Mol whereas the covalent contribution about 1.0(0.2) Kcal/Mol. JAGP reveales thus a promising WF for describing systems where both dispersive and covalent forces play an important role.

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。

↑