thank you.it seems somewhat complex.hehe 2008/2/19, Paolo Giannozzi <giannozz at nest.sns.it>: > > > On Feb 18, 2008, at 14:08 , xu yuehua wrote: > > > i am writing to enquire that is there a way to get the second order > > coefficient of Nonlinear Optical within PWSCF, directly or indirectly. > > second-order nonlinear optical coefficients, i.e. \gamma in the > following formula, where P is the induced polarization and E the > electric field: P=\alpha E + \beta E^2 + \gamma E^3 ? this is > the fourth-order derivative of the energy wrt electric field and > can be calculated using the second-order response to an > applied electric field. The latter is calculated by the phonon > code for the Raman calculation. The code already calculates > the nonlinear optical coefficient \beta (called "electro-optical > coefficients": I do not think this is correct, by the way). Static > calculations, though (\omega=0), and no ultrasoft PP. So all > ingredients are there, but require some programming. It is > something that I wanted to do (and still want to do: it is useful > to estimate how nonlinear optical properties change in phtalocyanines > when deposited on some surfaces and doped), but it requires an > amount of patience that I am afraid I no longer have. Anybody > interested? > > Paolo > --- > Paolo Giannozzi, Dept of Physics, University of Udine > via delle Scienze 208, 33100 Udine, Italy > Phone +39-0432-558216, fax +39-0432-558222 > > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum >
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