Abstract
The relative stabilities of the six lowest energy tautomers of the DNA base guanine have been investigated in the first excited singlet state, S1, employing the restricted open-shell Kohn–Sham (ROKS) method. Comparison of the S1 optimized geometries to the respective ground-state structures reveals large distortions for the keto tautomers, whereas the enol tautomers remain essentially planar. Harmonic vibrational spectra in the S1 state have been calculated using the ROKS potential energy surfaces. Adiabatic excitation energies together with characteristic vibrational features of the individual guanine tautomers enable us to unambiguously assign recent experimental IR-UV spectra. Velocity autocorrelation functions obtained from adiabatic excited state Car–Parrinello molecular dynamics simulations demonstrate that anharmonic effects only play a minor role.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
