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What theory is used for static nonlinear optics?

Posted: Wed Jan 31, 2018 1:59 am
by kurtg
Hi,

I found there are two independent subroutines in abinit. Both are calculating the nonlinear optical properties.

The frequency-dependent SHG susceptibility is calculated in 32_util/m_optic_tools.F90, which is following Sharma et al's paper [Phys. Rev. B 67, 165332 (2003)]. While the static nonlinear susceptibility d_ij(0) is calculated in 95_drive/nonlinear.F90. The latter one needs the third order derivative of energy, which is apparently based on a different theory. I couldn't find the theory used by this code from either the ABINIT user guide or in the code. Could anyone let me know the reference?

Also, does anyone have an idea why extrapolating the result from the first method to omega=0 does NOT even close to the result from the second method?

Re: What theory is used for static nonlinear optics?

Posted: Thu Feb 08, 2018 10:52 am
by ebousquet
Hi Kurtg,
The static non-linear susceptibility is using the theory written in this Veithen's paper:
https://journals.aps.org/prb/abstract/10.1103/PhysRevB.71.125107
There is presently a new and extended development of this non-linear response within DFPT but this is not yet available.
Best wishes,
Eric