Department of Chemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada.
J Chem Phys. 2017 May 21;146(19):194105. doi: 10.1063/1.4983281.
We propose a pruned multi-configuration time-dependent Hartree (MCTDH) method with systematically expanding nondirect product bases and use it to solve the time-independent Schrödinger equation. No pre-determined pruning condition is required to select the basis functions. Using about 65 000 basis functions, we calculate the first 69 vibrational eigenpairs of acetonitrile, CHCN, to an accuracy better than that achieved in a previous pruned MCTDH calculation which required more than 100 000 basis functions. In addition, we compare the new pruned MCTDH method with the established multi-layer MCTDH (ML-MCTDH) scheme and determine that although ML-MCTDH is somewhat more efficient when low or intermediate accuracy is desired, pruned MCTDH is more efficient when high accuracy is required. In our largest calculation, the vast majority of the energies have errors smaller than 0.01 cm.
我们提出了一种修剪后的多组态含时哈特里（MCTDH）方法，其基组采用系统扩展的非直积形式，并将其应用于求解时间无关的薛定谔方程。在选择基函数时，不需要预先设定修剪条件。使用约 65000 个基函数，我们计算了乙腈（CHCN）的前 69 个振动本征对，精度优于之前修剪后的 MCTDH 计算所需的精度，而后者需要超过 100000 个基函数。此外，我们还将新的修剪后的 MCTDH 方法与成熟的多层 MCTDH（ML-MCTDH）方案进行了比较，结果表明，尽管 ML-MCTDH 在需要低或中等精度时效率略高，但在需要高精度时修剪后的 MCTDH 效率更高。在我们最大的计算中，绝大多数能量的误差小于 0.01cm。
