CASPT2, CASSCF and non-adiabatic molecular dynamics (NAMD) studies on the low-lying electronic states of 1H-1,2,3-triazole photolysis

Abstract

The photolysis mechanisms of 1H-1,2,3-triazole and 1H-1,2,3-benzotriazole were elucidated by employing multiconfigurational methods (CASSCF and CASPT2) and non-adiabatic molecular dynamics.

Simulating Non‐Adiabatic Dynamics of Photoexcited Phenyl Azide: Investigating Electronic and Structural Relaxation en Route to the Formation of Phenyl Nitrene

“…The collected data is presented in Figure S4 and displays large deviations in a few trajectories. This is likely due to the constrained size of the active space, used to model actively evolving photo‐dissociation process [53] . Although it is possible to mitigate such high variations, with a larger active space and a greater number of roots in the state‐averaging scheme, the selected active space was a necessary compromise to manage computational cost in the simulation while performing qualitative analysis.…”

Vibrational spectroscopy by means of first‐principles molecular dynamics simulations

“…While in principle an exact solution of Equation ( 1) would be desirable, in practice further approximations have to be employed to make the solution tractable. Among the possible approximations for the time independent Schrödinger equation are tightbinding, [41][42][43][44] the Hartree-Fock method, 45 DFT, 46,47 Moller-Plesset perturbation theory, [48][49][50] approximations to relativistic quantum mechanics, 51,52 coupled cluster, [53][54][55] configuration interaction, 56 as well as combinations of methods either by embedding (e.g., hybrid quantum mechanics/molecular mechanics QM/MM 57 ) or by applying additional electronic structure methods to trajectories obtained from DFT-MD. MD calculations are carried out at finite temperatures.…”

From skin sensitizers to wastewater: the unknown photo-deactivation process of low-lying excited states of isothiazolinones. A non-adiabatic dynamics investigation

“…To achieve this, we employed state-of-the-art methodologies such as SA-CASSCF, MS-CASPT2, and nonadiabatic dynamics as literature indicates that these methods are capable of accurately describing complex photochemical processes. [33][34][35] The study begins with the validation of the chosen methods and the selected active space, taking into account both their suitability and limitations. Given the size and complexity of the isothiazolinones, we opted to employ a simpler model, isothiazol-3(2H)-one (isothiazolinone or ISO), as a representative of this compound class.…”