Search results for "caspt2"
showing 4 items of 14 documents
A theoretical study of the intramolecular charge transfer in 4-(dimethylamino)benzethyne
2014
We have investigated the non-adiabatic relaxation processes occurring in the singlet manifold of 4-(dimethylamino)benzethyne (DMABE){,} a molecule isoelectronic with 4-(dimethylamino)benzonitrile (DMABN) but lacking its characteristic dual fluorescence{,} using multireference perturbation theory methods. The results obtained point out to the existence of a two-fold decay mechanism in which the population of the initially accessed La state bifurcates towards a locally excited (LE) and a [small pi][sigma]* state. Further relaxation to an emitting intramolecular charge transfer (ICT) state is impeded due to the presence of pronounced energy barriers along their associated potential energy surf…
On the role of the triplet state in the cis/trans isomerization of rhodopsin: A CASPT2//CASSCF study of a model chromophore
2011
The possibility of population of the lowest-lying triplet state (T1) in the early events of the photochemical isomerization process of a model chromophore of Rhodopsin (Rh) has been analyzed using multireference perturbation theory (CASPT2//CASSCF) methods. It is shown that the characteristics of the isomerization process namely small S1−T1 gap, presence of hydrogen out of plane active vibrational modes, and existence of a dense manifold of vibrational states, render possible the fulfilment of the conditions needed for the population of T1. The possible consequences for the photochemistry and photophysics of Rh are also discussed. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem 111:3431–3…
Radiation damage in the DNA/RNA nucleobases: A theoretical study
2015
La comprensión de los mecanismos de daño en el DNA/RNA inducidos por luz UV y en condiciones de estrés reductor fue el principal objetivo de esta tesis. Para ello se usaron en monómeros y dímeros el método espacio activo complete campo autoconsistente / espacio activo completo teoría de perturbaciones hasta segundo orden de espacio activo complete(CASSCF/CASPT2) y estrategias computacionales precisas de determinación del camino de reacción. En cuanto al daño inducido por la luz UV en el ADN/ARN, hemos estudiado la fotoproducción de dímeros de pirimidina ciclobutano (CPDs) en nucleobases apiladas a través de las vías singlet y triplete. Estos mecanismos de fotodimerización son iniciados por …
Theoretical and computational studies of magnetic anisotropy and exchange coupling in molecular systems
2018
The field of molecular magnetism studies the magnetic properties of molecular systems as opposed to conventional metal-based magnets. The high chemical modifiability of the constituting molecules makes such materials highly versatile, and the small size of the building blocks leads to the rise of various quantum mechanical phenomena, such as tunneling and entanglement. These phenomena can then be further utilized in the construction of nanoscale quantum devices. This dissertation describes computational and theoretical studies in the field of molecular magnetism using state-of-the-art quantum chemical methods based on ab initio multireference approaches and broken symmetry density functional t…