Περίληψη:
To describe the molecular electronic structure of nucleic acid bases and
other heterocycles, we employ the Linear Combination of Atomic Orbitals
(LCAO) method, considering the molecular wave function as a linear
combination of all valence orbitals, i.e., 2s, 2px, 2py, 2pz orbitals
for C, N, and O atoms and 1s orbital for H atoms. Regarding the diagonal
matrix elements (also known as on-site energies), we introduce a novel
parameterization. For the non-diagonal matrix elements referring to
neighboring atoms, we employ the Slater-Koster two-center interaction
transfer integrals. We use Harrison-type expressions with factors
slightly modified relative to the original. We compare our LCAO
predictions for the ionization and excitation energies of heterocycles
with those obtained from Ionization Potential Equation of Motion Coupled
Cluster with Singles and Doubles (IP-EOMCCSD)/aug-cc-pVDZ level of
theory and Completely Normalized Equation of Motion Coupled Cluster with
Singles, Doubles, and non-iterative Triples (CR-EOMCCSD(T))/aug-cc-pVDZ
level of theory, respectively, (vertical values), as well as with
available experimental data. Similarly, we calculate the transfer
integrals between subsequent base pairs, to be used for a Tight-Binding
(TB) wire model description of charge transfer and transport along ideal
or deformed B-DNA. Taking into account all valence orbitals, we are in
the position to treat deflection from the planar geometry, e.g., DNA
structural variability, a task impossible for the plane Huckel approach
(i.e., using only 2pz orbitals). We show the effects of structural
deformations utilizing a 20mer evolved by Molecular Dynamics.
Συγγραφείς:
Mantela, Marilena
Simserides, Constantinos
Di Felice, Rosa
