# A model exact calculation of SHG coefficients in polysubstituted push-pull polyenes

Albert, IDL and Das, Puspendu K and Ramasesha, S (1990) A model exact calculation of SHG coefficients in polysubstituted push-pull polyenes. In: Chemical Physics Letters, 168 (5). pp. 454-460.

 PDF A_model_exact_calculation_of_SHG.pdf Restricted to Registered users only Download (565Kb) | Request a copy

## Abstract

We report the model exact second-harmonic generation coefficients $(\beta^{exact})$ in polysubstituted all-trans push—pull polyenes up to ten carbon atoms. The Pariser-Parr-Pople (PPP) model with standard molecular parameters has been used in the calculations. The two-state charge-transfer model in these systems is inadequate and an exact calculation is necessary to obtain reliable SHG coefficients. We find that for a fixed geometry, $\beta$ is enhanced if all the electron withdrawing substituents (pull) are successively placed from one end of the polyene chain and all the electron pushing groups (push) from the other. A twisted conformation of the polyene backbone leads to large SHG coefficients at the YAG laser frequency since the system approaches two-photon resonance. For a given chain length, the SHG coefficients increase with increase in the number of the push and pull groups.

Item Type: Journal Article Copyright of this article belongs to Elsevier Science B.V. SHG;push-pull polyenes;Pariser—Parr—Pople;PPP Division of Chemical Sciences > Solid State & Structural Chemistry UnitDivision of Chemical Sciences > Inorganic & Physical Chemistry 19 Feb 2008 19 Sep 2010 04:41 http://eprints.iisc.ernet.in/id/eprint/12708