Crossing conditions in coupled cluster theory

Abstract

We derive the crossing conditions at conical intersections between electronic states in coupled cluster theory, and show that if the coupled cluster Jacobian matrix is nondefective, two (three) independent conditions are correctly placed on the nuclear degrees of freedom for an inherently real (complex) Hamiltonian. Calculations using coupled cluster theory on an $2{}^1{A}^{\prime }/3{}^1{A}^{\prime }$ conical intersection in hypofluorous acid illustrate the nonphysical artifacts associated with defects at accidental same-symmetry intersections. In particular, the observed intersection seam is folded about a space of the correct dimensionality, indicating that minor modifications to the theory are required for it to provide a correct description of conical intersections in general. We find that an accidental symmetry allowed $1{}^{1}A"/2{}^{1}A"$ intersection in hydrogen sulfide is properly described, showing no artifacts as well as linearity of the energy gap to first order in the branching plane.

arXiv comment9 pages and 4 figures

References in corpus (1)

• Probing ultrafast ππ*/nπ* internal conversion in organic chromophores via K-edge resonant absorption

Cited by in corpus (10)

• Coupled Cluster Theory for Molecular Polaritons: Changing Ground and Excited States
• Equation-of-motion cavity quantum electrodynamics coupled-cluster theory for electron attachment
• Complex Ground-State and Excitation Energies in Coupled-Cluster Theory
• On the description of conical intersections between excited electronic states with LR-TDDFT and ADC(2)
• Unitary coupled-cluster based self-consistent polarization propagator theory: a quadratic unitary coupled-cluster singles and doubles scheme
• Prediction of Photodynamics of 200 nm Excited Cyclobutanone with Linear Response Electronic Structure and Ab Initio Multiple Spawning
• Non-adiabatic derivative coupling elements for the coupled cluster singles and doubles model
• Time-Dependent Equation-of-Motion Coupled-Cluster Simulations with a Defective Hamiltonian
• Rank-reduced equation-of-motion coupled cluster triples: an accurate and affordable way of calculating electronic excitation energies
• Equation-of-motion internally contracted multireference unitary coupled-cluster theory