A density matrix renormalization group method study of optical properties of porphines and metalloporphines

Kumar, Manoranjan and Pati, Anusooya Y and Ramasesha, S (2012) A density matrix renormalization group method study of optical properties of porphines and metalloporphines. In: Journal of Chemical Physics, The, 136 (1).

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Abstract

The symmetrized density matrix renormalization group method is used to study linear and nonlinear optical properties of free base porphine and metalloporphine. Long-range interacting model, namely, Pariser-Parr-Pople model is employed to capture the quantum many-body effect in these systems. The nonlinear optical coefficients are computed within the correction vector method. The computed singlet and triplet low-lying excited state energies and their charge densities are in excellent agreement with experimental as well as many other theoretical results. The rearrangement of the charge density at carbon and nitrogen sites, on excitation, is discussed. From our bond order calculation, we conclude that porphine is well described by the 18-annulenic structure in the ground state and the molecule expands upon excitation. We have modeled the regular metalloporphine by taking an effective electric field due to the metal ion and computed the excitation spectrum. Metalloporphines have D(4h) symmetry and hence have more degenerate excited states. The ground state of metalloporphines shows 20-annulenic structure, as the charge on the metal ion increases. The linear polarizability seems to increase with the charge initially and then saturates. The same trend is observed in third order polarizability coefficients. (C) 2012 American Institute of Physics. [doi: 10.1063/1.3671946]

Item Type:	Journal Article
Publication:	Journal of Chemical Physics, The
Publisher:	American Institute of Physics
Additional Information:	Copyright of this article belongs to American Institute of Physics.
Keywords:	ground states;many-body problems;organometallic compounds; polarisability;PPP calculations;quantum theory; renormalisation;triplet state
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	17 Feb 2012 11:40
Last Modified:	17 Feb 2012 11:40
URI:	http://eprints.iisc.ac.in/id/eprint/43530

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