Related Experiment Video
Updated: Jul 6, 2025

Experimental Methodology for Estimation of Local Heat Fluxes and Burning Rates in Steady Laminar Boundary Layer Diffusion Flames
Published on: June 1, 2016
A Local Diabatisation Method for Two-State Adiabatic Conical Intersections
Eva Vandaele1, Momir Mališ1, Sandra Luber1
1Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
Abstract:
A methodology to locally characterize conical intersections (CIs) between two adiabatic electronic states for which no nonadiabatic coupling (NAC) vectors are available is presented. Based on the Hessian and gradient at the CI, the branching space coordinates are identified. The potential energy surface around the CI in the branching space is expressed in the diabatic representation, from which the NAC vectors can be calculated in a wave-function-free, energy-based approach. To demonstrate the universality of the developed methodology, the minimum-energy CI (MECI) between the first (S1) and second (S2) singlet excited states of formamide is investigated at the state-averaged complete active space self-consistent field (SA-CASSCF) and extended multistate complete active space second-order perturbation theory (XMS-CASPT2) levels of theory. In addition, the asymmetrical MECI between the ground state (S0) and S1 of cyclopropanone is evaluated using SA-CASSCF, as well as (ME)CIs between the S1 and S2 states of benzene using SA-CASSCF and time-dependent density functional theory (TDDFT). Finally, a CI between the S1 and S2 excited states of thiophene was analyzed using TDDFT.
Related Concept Videos
Pressure and Volume in an Adiabatic Process
Adiabatic Processes for an Ideal Gas
Area Computation by the Alternative Coordinate Method
Design Example: Traverse Angle Computations
Horizontal Curve: Problem Solving
Path Between Thermodynamics States

