title: Assessment of Approximate Coupled-Cluster and Algebraic-Diagrammatic-Construction Methods for Ground- and Excited-State Reaction Paths and the Conical-Intersection Seam of a Retinal-Chromophore Model.
abstract: As a minimal model of the chromophore of rhodopsin proteins, the penta-2,4-dieniminium cation (PSB3) poses a challenging test system for the assessment of electronic-structure methods for the exploration of ground- and excited-state potential-energy surfaces, the topography of conical intersections, and the dimensionality (topology) of the branching space. Herein, we report on the performance of the approximate linear-response coupled-cluster method of second order (CC2) and the algebraic-diagrammatic-construction scheme of the polarization propagator of second and third orders (ADC(2) and ADC(3)). For the ADC(2) method, we considered both the strict and extended variants (ADC(2)-s and ADC(2)-x). For both CC2 and ADC methods, we also tested the spin-component-scaled (SCS) and spin-opposite-scaled (SOS) variants. We have explored several ground- and excited-state reaction paths, a circular path centered around the S1/S0 surface crossing, and a 2D scan of the potential-energy surfaces along the branching space. We find that the CC2 and ADC methods yield a different dimensionality of the intersection space. While the ADC methods yield a linear intersection topology, we find a conical intersection topology for the CC2 method. We present computational evidence showing that the linear-response CC2 method yields a surface crossing between the reference state and the first response state featuring characteristics that are expected for a true conical intersection. Finally, we test the performance of these methods for the approximate geometry optimization of the S1/S0 minimum-energy conical intersection and compare the geometries with available data from multireference methods. The present study provides new insight into the performance of linear-response CC2 and polarization-propagator ADC methods for molecular electronic spectroscopy and applications in computational photochemistry.
authors.affiliation: Max-Planck-Institut für Kohlenforschung , 45470 Mülheim an der Ruhr, Germany.
authors.forename: Deniz
authors.initials: D
authors.lastname: Tuna
authors.affiliation: Interdisciplinary Center for Scientific Computing, University of Heidelberg , 69120 Heidelberg, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Lefrancois
authors.affiliation: Department of Chemistry, Wrocław University of Technology , 50370 Wrocław, Poland.
authors.forename: Łukasz
authors.initials: Ł
authors.lastname: Wolański
authors.affiliation: Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States.
authors.forename: Samer
authors.initials: S
authors.lastname: Gozem
authors.affiliation: Institut de Physique et Chimie des Matériaux de Strasbourg & Labex NIE, Université de Strasbourg, CNRS UMR 7504 , Strasbourg 67034, France.
authors.forename: Igor
authors.initials: I
authors.lastname: Schapiro
authors.affiliation: Department of Chemistry, Wrocław University of Technology , 50370 Wrocław, Poland.
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Andruniów
authors.affiliation: Interdisciplinary Center for Scientific Computing, University of Heidelberg , 69120 Heidelberg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Dreuw
authors.affiliation: Department of Chemistry, Bowling Green State University , Bowling Green, Ohio 43402, United States.|Dipartimento di Biotecnologie, Chimica e Farmacia, Universitá de Siena , 53100 Siena, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Olivucci
mesh_terms: D008958:Models, Molecular; D011789:Quantum Theory; D012172:Retinaldehyde / Q000737:chemistry*; D012243:Rhodopsin / Q000737:chemistry*
chemical_list: D012243:Rhodopsin; D012172:Retinaldehyde