A complete description of tunnelling using direct quantum dynamics simulation: Salicylaldimine proton transfer.
A complete description of tunnelling using direct quantum dynamics simulation: Salicylaldimine proton transfer.
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DOI：
10.1063/1.4929478
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发表时间：
2015-08
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影响因子：
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通讯作者：
I. Polyak;Charlotte S. M. Allan;G. Worth
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文献类型：
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作者：
I. Polyak;Charlotte S. M. Allan;G. Worth
我们在这里使用水杨醛亚胺中的分子内质子转移作为模型系统，最终证明变分多配置高斯（vMCG）方法收敛于多维隧道问题的基于网格的全量子动力学多配置时间相关Hartree结果。在6- 31 G * 基组下由Hartree-Fock能得到13维模型势能面，并以沿跃迁模的通量算符沿着的期望值作为基准特征.除了使用局部调和近似和中等数量的基函数在模型表面上显示vMCG方法的出色收敛性之外，我们还表明vMCG的直接动力学版本也表现得非常好，通常需要相同数量的高斯收敛，并且如果在精确拟合的表面上获得精确的结果，则收敛到精确的结果。最后，我们做了一个重要的观察，高斯基函数的宽度必须非常仔细地选择，以获得准确的结果与使用冻结宽度近似。
We demonstrate here conclusively that the variational multiconfiguration Gaussian (vMCG) method converges to the grid based full quantum dynamics multiconfiguration time-dependent Hartree result for a tunnelling problem in many dimensions, using the intramolecular proton transfer in salicylaldimine as a model system. The 13-dimensional model potential energy surface was obtained from Hartree Fock energies with the 6-31G* basis set and the expectation value of the flux operator along the transition mode was used as a benchmark characteristic. As well as showing excellent convergence of the vMCG method on the model surface using a local harmonic approximation and a moderate number of basis functions, we show that the direct dynamics version of the vMCG also performs very well, usually needs the same number of Gaussians to converge, and converges to exact results if those are obtained on an accurately fitted surface. Finally, we make an important observation that the width of the Gaussian basis functions must be chosen very carefully to obtain accurate results with the use of the frozen-width approximation.