Otto, F; Chiang, Y-C; Peláez, D; (2017) Accuracy of Potfit-based potential representations and its impact on the performance of (ML-)MCTDH. Chemical Physics , 509 pp. 116-130. 10.1016/j.chemphys.2017.11.013.

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Abstract

Quantum molecular dynamics simulations with MCTDH or ML-MCTDH perform best if the potential energy surface (PES) has a sum-of-products (SOP) or multi-layer operator (MLOp) structure. Here we investigate four different POTFIT-based methods for representing a general PES as such a structure, among them the novel random-sampling multi-layer Potfit (RS-MLPF). We study how the format and accuracy of the PES representation influences the runtime of a benchmark (ML-)MCTDH calculation, namely the computation of the ground state of the H3O2− ion. Our results show that compared to the SOP format, the MLOp format leads to a much more favorable scaling of the (ML-)MCTDH runtime with the PES accuracy. At reasonably high PES accuracy, ML-MCTDH calculations thus become up to 20 times faster, and taken to the extreme, the RS-MLPF method yields extremely accurate PES representations (global root-mean-square error of ∼0.1 cm−1) which still lead to only moderate computational demands for ML-MCTDH.

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