[QE-users] phonon dispersion relation from the full IFCs

[Stefano Baroni]

The full dynamical matrix, including long-range forces, is computed by ph.x. The latter do not require any fine grid, but just the computation of Born effective charges, as explained in: P. Giannozzi et al, PRB 43, 7231 (1991), Eq. 18.  Regards — SB 

> On 8 Jan 2020, at 13:49, jqhuang16b at imr.ac.cn wrote:
> 
> Dear all,
> 
> As we know, the short-ranged IFCs are available by QE. The dynamical matrices are obtained by making inverse Fourier transformation of the short-ranged IFCs, and then add back the long-ranged dipole-dipole contribution in the reciprocal space. This paper(X. Gonze et al, PRB 50. 13035 (1994)) provides the formula of long-ranged force constants. I wonder that is it feasible to obtain the correct phonon spectrum from the full IFCs(short+long)? Of course, the long-ranged IFCs should be gotten in a much longer range(maybe 100*100*100).
> 
> Any comments will be appreciated!
> 
> --
> Jian-qi Huang
> 
> Magnetism and Magnetic Materials Division
> Institute of Metal Research 
> Chinese Academy of Sciences
> 72 Wenhua Road, Shenyang 110016, China
> 
> email:jqhuang16b at imr.ac.cn <mailto:jqhuang16b at imr.ac.cn>
> 
> 
> 
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— 
Stefano Baroni - Trieste —  http://stefano.baroni.me <http://stefano.baroni.me/> 




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