Linked Life Data

19412906

Source:http://linkedlifedata.com/resource/pubmed/id/19412906

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2009-11-30
pubmed:abstractText
Electronic spectra of guanine in the gas phase and in water were studied by quantum mechanical/molecular mechanical (QM/MM) methods. Geometries for the excited-state calculations were extracted from ground-state molecular dynamics (MD) simulations using the self-consistent-charge density functional tight binding (SCC-DFTB) method for the QM region and the TIP3P force field for the water environment. Theoretical absorption spectra were generated from excitation energies and oscillator strengths calculated for 50 to 500 MD snapshots of guanine in the gas phase (QM) and in solution (QM/MM). The excited-state calculations used time-dependent density functional theory (TDDFT) and the DFT-based multireference configuration interaction (DFT/MRCI) method of Grimme and Waletzke, in combination with two basis sets. Our investigation covered keto-N7H and keto-N9H guanine, with particular focus on solvent effects in the low-energy spectrum of the keto-N9H tautomer. When compared with the vertical excitation energies of gas-phase guanine at the optimized DFT (B3LYP/TZVP) geometry, the maxima in the computed solution spectra are shifted by several tenths of an eV. Three effects contribute: the use of SCC-DFTB-based rather than B3LYP-based geometries in the MD snapshots (red shift of ca. 0.1 eV), explicit inclusion of nuclear motion through the MD snapshots (red shift of ca. 0.1 eV), and intrinsic solvent effects (differences in the absorption maxima in the computed gas-phase and solution spectra, typically ca. 0.1-0.3 eV). A detailed analysis of the results indicates that the intrinsic solvent effects arise both from solvent-induced structural changes and from electrostatic solute-solvent interactions, the latter being dominant.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
1096-987X
pubmed:author
pubmed:copyrightInfo
Copyright 2009 Wiley Periodicals, Inc.
pubmed:issnType
Electronic
pubmed:day
15
pubmed:volume
31
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
90-106
pubmed:meshHeading
pubmed:year
2010
pubmed:articleTitle
QM/MM calculation of solvent effects on absorption spectra of guanine.
pubmed:affiliation
Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't