The Role of Aqueous Solvation on the Intersystem Crossing of Nitrophenols.

The photochemistry of nitrophenols is a source of smog as nitrous acid is formed from their photolysis. Nevertheless, computational studies of the photochemistry of these widespread toxic molecules are scarce. In this work, the initial photodeactivation of -nitrophenol and -nitrophenol is modeled, both in gas phase and in aqueous solution to simulate atmospheric and aerosol environments.

A Local Diabatisation Method for Two-State Adiabatic Conical Intersections.

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.

Synthesis of Mesodiphenylhelianthrene from 1-Aminoanthraquinone and the Structural Elucidation of Its Endoperoxide Species after Irradiation.

A safe, five-step synthetic route to yield the reliable chemical actinometer, mesodiphenylhelianthrene (), is reported from a commercially available compound. Full characterization of the intermediates of the synthetic route and the final product are presented together with four crystal structures of intermediates and . The usage of the actinometer is described, and finally, the structure of the endoperoxide species (), which is formed after irradiation of , has been elucidated experimentally and theoretically.

Spin-Orbit Couplings for Nonadiabatic Molecular Dynamics at the ΔSCF Level.

A procedure for the calculation of spin-orbit coupling (SOC) at the delta self-consistent field (ΔSCF) level of theory is presented. Singlet and triplet excited electronic states obtained with the ΔSCF method are expanded into a linear combination of singly excited Slater determinants composed of ground electronic state Kohn-Sham orbitals. This alleviates the nonorthogonality between excited and ground electronic states and introduces a framework, similar to the auxiliary wave function at the time-dependent density functional theory (TD-DFT) level, for the calculation of observables.

The ΔSCF method for non-adiabatic dynamics of systems in the liquid phase.

Computational studies of ultrafast photoinduced processes give valuable insights into the photochemical mechanisms of a broad range of compounds. In order to accurately reproduce, interpret, and predict experimental results, which are typically obtained in a condensed phase, it is indispensable to include the condensed phase environment in the computational model. However, most studies are still performed in vacuum due to the high computational cost of state-of-the-art non-adiabatic molecular dynamics (NAMD) simulations.

The photodissociation of solvated cyclopropanone and its hydrate explored non-adiabatic molecular dynamics using ΔSCF.

The decay of cyclopropanone is a typical example of a photodecomposition process. Ethylene and carbon monoxide are formed following the excitation to the first singlet excited state through a symmetrical or asymmetrical pathway. The results obtained with non-adiabatic molecular dynamics (NAMD) using the delta self-consistent field (ΔSCF) method correspond well to previous experimental and multireference theoretical studies carried out in the gas phase.

The Quantization of the E ⊗ e Jahn-Teller Hamiltonian.

The E ⊗ e Jahn-Teller Hamiltonian in the Bargmann-Fock representation gives rise to a system of two coupled first-order differential equations in the complex field, which may be rewritten in the Birkhoff standard form. General leapfrog recurrence relations are derived, from which the quantized solutions of these equations can be obtained. The results are compared to the analogous quantization scheme for the Rabi Hamiltonian.