Thank you, sir. I have another confusion now. The long-range dynamical matrix should not change too much if I reset alph to a larger number, given that it is convergent. However, I set alph= 2.0d0 and obtain a very different long-range dynamical matrix. Where is the problem?
> -----原始邮件----- > 发件人: "Stefano Baroni" <[email protected]> > 发送时间: 2020-01-11 02:47:40 (星期六) > 收件人: "Quantum ESPRESSO users Forum" <[email protected]> > 抄送: > 主题: Re: [QE-users] phonon dispersion relation from the full IFCs > > 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 _______________________________________________ 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
