Aarhus University Seal / Aarhus Universitets segl

MR-MCTDH[n]: Flexible Configuration Spaces and Nonadiabatic Dynamics within the MCTDH[n] Framework

Publikation: Bidrag til tidsskrift/Konferencebidrag i tidsskrift /Bidrag til avisTidsskriftartikelForskningpeer review


  • Niels Kristian Madsen
  • ,
  • Mads Bøttger Hansen
  • ,
  • Graham A. Worth, University College London
  • ,
  • Ove Christiansen

Solving the time-dependent Schrödinger equation (TDSE) for large molecular systems is a complicated task due to the inherent exponential scaling of the problem. One of the most successful and versatile methods for obtaining numerically converged solutions for small to medium-sized systems is multiconfiguration time-dependent Hartree (MCTDH). In a recent publication [J. Chem. Phys.2020, 152, 084101] we introduced a hierarchy of approximations to the MCTDH method which mitigate the exponential scaling by truncating the configuration space based on a maximum excitation level w.r.t. a selected reference configuration. The MCTDH[n] methods are able to treat large systems, but the single-reference Ansatz is not optimal in cases where one (or a few) degrees of freedom are special. Examples could be double-well systems, intramolecular vibrational-energy redistribution (IVR) calculations, or nonadiabatic dynamics. In this work we introduce a multireference (MR) extension to the MCTDH[n] methods where selected higher-order excitations for the special degrees of freedom can be introduced in a simple but flexible way. The resulting MR-MCTDH[n] methods allow for, for example, treating nonadiabatic dynamics within the single-set formalism with the wave packets on each electronic surface described using the same level of approximation. Example calculations are performed on formyl fluoride (IVR), salicylaldimine (double well), and pyrazine (nonadiabatic dynamics). The results show that fast convergence is achieved by extending the configuration space in the special modes that govern the quantum dynamics.

TidsskriftJournal of Chemical Theory and Computation
Sider (fra-til)4087-4097
Antal sider11
StatusUdgivet - 14 jul. 2020

Se relationer på Aarhus Universitet Citationsformater

ID: 194007095