# Dynamical pruning of the multiconfiguration time-dependent Hartree method (DP-MCTDH): An efficient approach for multidimensional quantum dynamics

## TL;DR

This paper introduces two dynamical pruning strategies for the multiconfiguration time-dependent Hartree method, significantly improving computational efficiency for multidimensional quantum dynamics simulations.

## Contribution

It develops and demonstrates two novel dynamical pruning strategies for MCTDH, enhancing efficiency and applicability to larger, more complex quantum systems.

## Key findings

- Pruning primitive basis functions reduces computational cost for small systems.
- Pruning SPF configurations yields speed-ups of 5 to 50 times.
- Strategies enable handling higher-dimensional systems more efficiently.

## Abstract

We present two strategies for combining dynamical pruning with the multiconfiguration time-dependent Hartree method (DP-MCTDH), where dynamical pruning means on-the-fly selection of relevant basis functions. The first strategy prunes the primitive basis that represents the single-particle functions (SPFs). This is useful for smaller systems that require many primitive basis functions per degree of freedom, as we will illustrate for NO$_2$. Furthermore, this allows for higher-dimensional mode combination and partially lifts the sum-of-product-form requirement onto the structure of the Hamiltonian, as we illustrate for nonadiabatic 24-dimensional pyrazine. The second strategy prunes the set of configurations of SPF at each time step. We show that this strategy yields significant speed-ups with factors between 5 and 50 in computing time, making it competitive with the multilayer MCTDH method.

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Source: https://tomesphere.com/paper/1705.02769