Breakdown of the first hyperpolarizability/bond-length alternation parameter relationship.
We have investigated the dependence of the static first hyperpolarizability on the bond-length alternation (BLA) parameter. Our analysis indicates that the validity of the first hyperpolarizability/BLA parameter relationship is restricted to the no-field, vacuum, limit, while it successively breaks down along with increasing polarity of a surrounding medium, becoming invalid, for instance, in an aqueous solution. This contention is based on a series of TD-DFT, TD-DFT/PCM and hybrid TD-DFT/MM calculations of the first hyperpolarizability for a set of molecular configurations generated from Car-Parrinello hybrid QM/MM simulations of the stilbazolium merocyanine chromophore in chloroform and water solvents, and on a rationalization by means of the two-state model for the first hyperpolarizability. The BLA dependence of the three parameters entering the two-state model is shown to be qualitatively different in vacuum and in solvents. Particularly, in the vacuum case, the difference between ground and excited state dipole moments goes to zero for a vanishing BLA, which is not true in the presence of an aqueous medium. In the aqueous medium, an opposing behavior of the parameters involved in the two-state model results in an almost constant first hyperpolarizability with varying BLA parameter.
Murugan
N Arul
NA
Department of Theoretical Chemistry, School of Biotechnology, Royal Institute of Technology, SE-10691 Stockholm, Sweden.
Kongsted
Jacob
J
Rinkevicius
Zilvinas
Z
Agren
Hans
H
Science. 1991 Apr 5;252(5002):103-6
17739081
Chemphyschem. 2003 Oct 17;4(10):1084-94
14596006
J Chem Phys. 2007 Apr 21;126(15):154112
17461619
Chem Rev. 1999 Aug 11;99(8):2161-2200
11849023
Proc Natl Acad Sci U S A. 1993 Dec 1;90(23):11297-301
11607441
Science. 1994 Jul 29;265(5172):632-5
17752759
J Phys Chem A. 2009 Apr 30;113(17):4833-9
19341255
J Mol Biol. 1976 May 15;103(2):227-49
985660
Chem Rev. 2000 May 10;100(5):1741-1754
11777418
Annu Rev Phys Chem. 2002;53:467-505
11972016
Chem Commun (Camb). 2006 Jan 14;(2):131-4
16372084
J Phys Chem B. 2009 Jan 29;113(4):1012-21
19123823