1.0 tons is 1000000000 times larger than 1.0 mg. A very large number indeed! SB
-- Stefano Baroni, Trieste -- swift message written and sent on the go > On 10 Jan 2020, at 18:03, [email protected] wrote: > > Thank you so much, professor. I really appreciate your scrupulous reply over > and over again. > In the QE code(subroutine rgd_dyn) of computing the rigid-ion (long-range) > term, it is commented that > "Only the G-space term is implemented: the Ewald parameter alpha must be > large enough to have negligible r-space contribution". > But in the following value assignment, alph= 1.0d0, not a very large number. > I think such a value will not make the real-space term vanish in the Ewald > summation. > How to understand this? > > >> -----原始邮件----- >> 发件人: "Lorenzo Paulatto" <[email protected]> >> 发送时间: 2020-01-10 17:19:48 (星期五) >> 收件人: [email protected] >> 抄送: >> 主题: Re: [QE-users] phonon dispersion relation from the full IFCs >> >>> Is it equivalent to the regular adopted Ewald summation method in >>> mathematics? >> >> I think you forgot to attach the paper in question... >> >> That said, if there is not lo-to splitting, there are no effectiv >> charges and no long-range interaction. Than there is no problem doing >> Fourier interpolation. >> >> 2D is a bit special, but the QE code has special techniques to deal with >> 2D phonon interpolation, I think it is explained in Phys. Rev. B 94, 085415 >> >> cheers >> >>> >>> 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 >>> >> >> -- >> 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 _______________________________________________ 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
