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Research Letters in Physical Chemistry
Volume 2007 (2007), Article ID 85978, 5 pages
http://dx.doi.org/10.1155/2007/85978
Research Letter

Structure of Low-Lying Excited States of Guanine in DNA and Solution: Combined Molecular Mechanics and High-Level Coupled Cluster Studies

William R. Wiley Environmental Molecular Sciences Laboratory, Battelle, Pacific Northwest National Laboratory, K1-96, P.O. Box 999, Richland, WA 99352, USA

Received 25 June 2007; Accepted 16 September 2007

Academic Editor: Sylvio Canuto

Copyright © 2007 Karol Kowalski and Marat Valiev. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

High-level ab-initio equation-of-motion coupled-cluster methods with singles, doubles, and noniterative triples are used, in conjunction with the combined quantum mechanical molecular mechanics approach, to investigate the structure of low-lying excited states of the guanine base in DNA and solvated environments. Our results indicate that while the excitation energy of the first excited state is barely changed compared to its gas-phase counterpart, the excitation energy of the second excited state is blue-shifted by 0.24 eV.