### Isotropic averages in dalton for 2nd order hyperpolarizability

Posted:

**25 Nov 2018, 07:34**I'm trying to calculate the isotropic 2nd hyperpolarizability to compare against bulk liquid and gas third order susceptibility measurements from OKE, THG, and Z-scan experiments. Looking at the manual it appears that isotopic averaging is only implemented for Coupled Cluster Calculation and only for gamma parallel and gamma perpendicular. I would like to have access to the full set relevant isotropic gammas to compare against experiment but I don't know how to convert between the gamma output of dalton and the bulk response of chi(3).

Reading Boyd I realize there must be corrections for the number density of molecules and local-field corrections but I'm stuck in how to calculate the effect of orientational averaging in the isotropic material. Part of this problem is due to my confusion about how Dalton defines it's molecular axes and how to relate that to the lab frame. With that being said, how does Dalton define its molecular frame axes and are there any helpful resources that I may have missed?

Additionally, can dalton calculate these isotropic averages directly? If so through which sub-module?

Answers and/or references to any part of this question are appreciated.

Reading Boyd I realize there must be corrections for the number density of molecules and local-field corrections but I'm stuck in how to calculate the effect of orientational averaging in the isotropic material. Part of this problem is due to my confusion about how Dalton defines it's molecular axes and how to relate that to the lab frame. With that being said, how does Dalton define its molecular frame axes and are there any helpful resources that I may have missed?

Additionally, can dalton calculate these isotropic averages directly? If so through which sub-module?

Answers and/or references to any part of this question are appreciated.