CCL:G: How to calculate Hyperpolarizability using G03



Hi Veerpandian,

First hyperpolarizability (Beta) is a third rank tensor that can be described by a 3x3x3 matrix. The 27 components of the 3D matrix can be reduced to 10 components due to the Kleinman symmetry. It can be given in the lower tetrahedral format. It is obvious that the lower part of the 3x3x3 matrix (cube) is a tetrahedral.

you can exploit #P and POLAR keywords to compute hyperpolarizability in Gaussian.

For an example: ‘#P B3LYP/6-31G** POLAR gives you the 10 components of lower tetrahedral tensor. The 10 components of this tensor is Bxxx, Bxxy, Bxyy, Byyy, Bxxz, Bxyz, Byyz, Bxzz, Byzz, and Bzzz; respectively.

The the total hyperpolarizability (Btot) can be calculated using following equations.

1) The components of beta can be calculated using the following equation

B_i = B_iii + 1/3 sum (B_ijj+B_jij+B_ijj)  i = x,y,z

Using the x, y and z components of B, the magnitude of the first hyperpolarizability tensor can be calculated.

B_tot = (Bx^2+By^2+Bz^2)^1/2

The complete equation for calculating the magnitude of B from Gaussian output is given as follows.

b_tot = {(b_xxx+b_xyy+b_xzz)^2+(b_yyy+b_yzz+yxx)^2+(b_zzz+b_zxx+b_zyy)^2}^1/2

Since the values of the first hyperpolarizability tensors of the output file of Gaussian are reported in atomic units (a.u.), the calculated values should be converted into electrostatic units (1 a.u. = 8.6393x10^-33 esu).

you can find more details form
J. Mol. Struc. (Theochem) y2002,v617,pp169–175
http://dx.doi.org/10.1016/S0166-1280(02)00419-0

Regards,
-Sahan-

/*---------------------------*/
K. Sahan Thanthiriwatte, Ph.D.
Center for Computational Molecular Science & Technology,
School of Chemistry and Biochemistry
Georgia Institute of Technology
Atlanta, GA 30332
Tel: 404-496-8244, Fax: 404-894-7452


On Mon, Jan 10, 2011 at 4:52 AM, veera pandian ponnuchamy veera.pandi33[a]gmail.com <owner-chemistry]^[ccl.net> wrote:
>
> Sent to CCL by: "veera pandian ponnuchamy" [veera.pandi33(_)gmail.com]
> I am a beginner in computational chemistry doing my M.Sc project on prediction of hyperpolarizability of organic molecule using Gaussian 03/09. When I use polar=enonly in the route section, the program completed successfully. I dont know which value I have to take from the output to get the hyperpolarizability? Whether my keyword is right or wrong? Any suggestions will be helpful
>
> Thanks in advance.
>
> By
> Veerpandian.P
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