Thank you for the detailed answer, professor. ---"I think you should explain WHY you want to do this, and you may get some better answer." The reason I want to do so is because I have read one paper which adopts the full IFCs to reproduce the phonon dispersion perfectly. Moreover, the result shows there is no LO-TO splitting at Gamma point in the 2D case, which agrees with the theoretical prediction of optical dispersion for 2D materials. This is really intresting for me, but I am unable to judge its reasonableness. I have attached the paper for the reference. Now my confusion about the treatment of the dipole-dipole interaction is why not deal with the long-range dynamical contribution by making inverse Fourier transform just the same way as short-range contribution, given that the formula of long-range IFCs is already available(X. Gonze et al, PRB 50. 13035 (1994)). Is it equivalent to the regular adopted Ewald summation method in mathematics?
With thanks and best regards ! Happy New Year ! -- Jian-qi Huang Magnetism and Magnetic Materials Division Institute of Metal Research Chinese Academy of Sciences 72 Wenhua Road, Shenyang 110016, China email:[email protected] > -----原始邮件----- > 发件人: "Lorenzo Paulatto" <[email protected]> > 发送时间: 2020-01-09 03:56:21 (星期四) > 收件人: [email protected] > 抄送: > 主题: Re: [QE-users] phonon dispersion relation from the full IFCs > > > Thank you for reply, professor. I understand the regular routine > > implemented in QE where the long-range contribution is added in > > reciprocal space. My point is can I get the correct dynamical matrix > > just by making inverse Fourier transformation of the full(short+long) > > IFCs in a large real space? > > > > The dynamical matrix at Gamma is discontinuity with respect to the > points nearby, which would make any Fourier transform impossible to > converge. > > I think you should explain WHY you want to do this, and you may get some > better answer. > > In practice, if I was obliged at gunpoint, I would replace the dynamical > matrix file at Gamma (typically dyn1) with one computed very close to > Gamma, let's say q=0.001,0,0. Edit the file to trick q2r into thinking > that it was done at exactly Gamma, and see was comes out. > > If the material has a non-analytic term (i.e. the long range term > depends on the direction), this will definitely not work. Otherwise, you > may get something decent. > > > cheers > > > > -- > Lorenzo Paulatto - Paris > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
