title: Benchmark studies on the building blocks of DNA. 3. Watson-Crick and stacked base pairs.
abstract: Excited states of stacked adenine-thymine and guanine-cytosine pairs as well as the Watson-Crick pair of guanine-thymine have been investigated using the equation of motion coupled-cluster (EOM-CC) method with single and double as well as approximate triple excitations. Transitions have been assigned, and the form of the excitations has been analyzed. The majority of the excitations could be classified as localized on the nucleobases, but for all three studied systems, charge-transfer (CT) transitions could also be identified. The main aim of this study was to compare the performance of lower-level methods (ADC(2) and TDDFT) to the high-level EOM-CC ones. It was shown that both ADC(2) and TDDFT with long-range correction have nonsystematic error in excitation energies, causing alternation of the energetic ordering of the excitations. Considering the high costs of the EOM-CC calculations, there is a need for reliable new approximate methods.
authors.affiliation: Institute of Chemistry, Eötvös University, H-1518 Budapest, P.O. Box 32, Hungary. szalay@chem.elte.hu
authors.forename: Péter G
authors.initials: PG
authors.lastname: Szalay
authors.forename: Thomas
authors.initials: T
authors.lastname: Watson
authors.forename: Ajith
authors.initials: A
authors.lastname: Perera
authors.forename: Victor
authors.initials: V
authors.lastname: Lotrich
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Bartlett
mesh_terms: D000225:Adenine / Q000737:chemistry; D020029:Base Pairing; D003596:Cytosine / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D006147:Guanine / Q000737:chemistry; D006860:Hydrogen Bonding; D008958:Models, Molecular; D011789:Quantum Theory; D013941:Thymine / Q000737:chemistry
chemical_list: D006147:Guanine; D003596:Cytosine; D004247:DNA; D000225:Adenine; D013941:Thymine