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Large-scale first principles configuration interaction calculations of optical absorption in aluminum clusters

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Title Large-scale first principles configuration interaction calculations of optical absorption in aluminum clusters
 
Creator SHINDE, R
SHUKLA, A
 
Subject LYING ELECTRONIC STATES
S-P HYBRIDIZATION
METAL MICROCLUSTERS
PHOTOELECTRON-SPECTROSCOPY
SODIUM CLUSTERS
SHELL STRUCTURE
AB-INITIO
EVOLUTION
ENERGIES
AL2
 
Description We report the linear optical absorption spectra of aluminum clusters Al-n (n = 2-5) involving valence transitions, computed using the large-scale all-electron configuration interaction (CI) methodology. Several low-lying isomers of each cluster were considered, and their geometries were optimized at the coupled-cluster singles-doubles (CCSD) level of theory. With these optimized ground-state geometries, excited states of different clusters were computed using the multi-reference singles-doubles configuration-interaction (MRSDCI) approach, which includes electron correlation effects at a sophisticated level. These CI wave functions were used to compute the transition dipole matrix elements connecting the ground and various excited states of different clusters, and thus their photoabsorption spectra. The convergence of our results with respect to the basis sets, and the size of the CI expansion, was carefully examined. Our results were found to be significantly different as compared to those obtained using time-dependent density functional theory (TDDFT) [Deshpande et al. Phys. Rev. B: Condens. Matter Mater. Phys., 2003, 68, 035428]. When compared to the available experimental data for the isomers of Al-2 and Al-3, our results are in very good agreement as far as important peak positions are concerned. The contribution of configurations to many body wave functions of various excited states suggests that in most cases optical excitations involved are collective, and plasmonic in nature.
 
Publisher ROYAL SOC CHEMISTRY
 
Date 2014-12-28T12:06:32Z
2014-12-28T12:06:32Z
2014
 
Type Article
 
Identifier PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 16(38)20714-20723
1463-9076
1463-9084
http://dx.doi.org/10.1039/c4cp02232g
http://dspace.library.iitb.ac.in/jspui/handle/100/16438
 
Language English