Optical absorption in boron clusters B6 and B6+: a first principles configuration interaction singles approach*
Department of Physics, Indian Institute of Technology Bombay, 400076 Mumbai, Maharashtra, India
Received: 31 August 2012
Received in final form: 27 February 2013
Published online: 7 May 2013
The linear optical absorption spectra in neutral boron cluster B6 and cationic B6+ are calculated using a first principles correlated electron approach. The geometries of several low-lying isomers of these clusters were optimized at the coupled-cluster singles doubles (CCSD) level of theory. With these optimized ground-state geometries, excited states of different isomers were computed using the configuration-interaction singles (CIS) approach. The many-body wavefunctions of various excited states have been analyzed and the nature of optical excitation involved are found to be of collective, plasmonic type. We also benchmark our CIS results against more sophisticated equation-of-motion (EOM) CCSD approach for a few isomers.
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2013