Linear and nonlinear optical properties of expanded porphyrins: a DMRG study

Thomas, Simil and Pati, YA and Ramasesha, S (2013) Linear and nonlinear optical properties of expanded porphyrins: a DMRG study. In: Journal of Physical Chemistry A, 117 (33). pp. 7804-7809.

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Abstract

We study absorption spectra and two photon absorption coefficient of expanded porphyrins (EPs) by the density matrix renormalization group (DMRG) technique. We employ the Pariser-Parr-Pople (PPP) Hamiltonian which includes long-range electron-electron interactions. We find that, in the 4n+2 EPs, there are two prominent low-lying one-photon excitations, while in 4n EPs, there is only one such excitation. We also find that 4n+2 EPs have large two-photon absorption cross sections compared to 4n EPs. The charge density rearrangement in the one-photon excited state is mostly at the pyrrole nitrogen site and at the meso carbon sites. In the two-photon states, the charge density rearrangement occurs mostly at the aza-ring sites. In the one-photon state, the C-C bond length in aza rings shows a tendency to become uniform. In the two-photon state, the bond distortions are on C-N bonds of the pyrrole ring and the adjoining C-C bonds which connect the pyrrole ring to the aza or meso carbon sites.

Item Type:	Journal Article
Publication:	Journal of Physical Chemistry A
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society.
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	27 Sep 2013 05:00
Last Modified:	27 Sep 2013 05:00
URI:	http://eprints.iisc.ac.in/id/eprint/47435

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