Time-dependent vibrational coupled cluster with variationally optimized time-dependent basis sets

Abstract

Time-dependent vibrational coupled cluster with variationally optimized timedependent basis sets

A general implementation of time-dependent vibrational coupled-cluster theory

“…The theory of timedependent vibrational coupled cluster with time-dependent modals (TDMVCC) has been presented in Ref. 25 together with an inefficient pilot implementation used for demonstrating its accuracy and theoretical benefits. Developing open-ended TDMVCC implementations using the automatic framework described in this paper is an exciting challenge for future developments in the field, which will hopefully allow highly accurate quantum-dynamics simulations of large molecules to be performed.…”

“…52 and used later in Refs. 11,12,15,24,and 25. As in previous studies, we employ the Dormand-Prince 8(5,3) explicit Runge-Kutta method with adaptive step-size control and dense output. 53 We note that all EOMs were propagated without noticeable problems with stability and no need was found for symplectic integrators, 21 but the adaptive step-size control is important.…”

“…Note that a fully exponential parameterization of both the bra and the ket is required in order to obtain complete separability of both EOMs and all observables, 24 but the time-dependent extended vibrational coupled cluster (TDEVCC) approach implementing this so far appears too complicated to be practically applicable beyond systems where exact results can be obtained. Note also that very recently equations for a time-dependent CC with a time-dependent basis have been derived, 25 but while this method may end up being sufficiently efficient, its general implementation is even more complicated than the TDVCC theory considered here by a significant margin.…”

Calculating vibrational excitation energies using tensor-decomposed vibrational coupled-cluster response theory

“…The CP-VCC response equations have been implemented in the Molecular Interactions, Dynamics And Simulations Chemistry Program Package (MidasCpp), 51 which includes implementations of an array of methods for solving both the time-independent 5,8,11,52 and time-dependent [53][54][55][56] vibrational Schrödinger equations, tools for coordinate optimization, 57,58 automatic PES generation, 40,44,59 etc.…”

Time‐dependent coupled‐cluster theory

“…In Ref. [133], Madsen et al presented an advanced implementation of orbital‐adaptive theory with very promising results, including the apparent cure of exploding amplitude norms in TDVCC[ n ] calculations for the water potential‐energy surface. This corroborates findings by Kristiansen et al, 93 who applied TDNOCC theory to electronic systems.…”