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Re: [abinit-forum] the difference of the Phonon frequencies


Chronological Thread 
  • From: verstraete@pcpm.ucl.ac.be
  • To: forum@abinit.org
  • Subject: Re: [abinit-forum] the difference of the Phonon frequencies
  • Date: Wed, 18 Feb 2004 15:16:49 +0100 (CET)


Probably the acoustic sum rule, which has been imposed in anaddb. If the
frequencies you gave were for the gamma point, you are very far from
convergence (ecut, kpt). Send more complete information for more complete
answers.

Otherwise, since I see you do have 3 0.0 eigenvalues in anaddb, you may
have an actual instability (negative phonon mode), if your system is not
at a true equilibrium.


Matthieu


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Matthieu Verstraete mailto:verstraete@pcpm.ucl.ac.be
PCPM, Boltzmann, pl. Croix du Sud, 1 tel: 010/ 47 33 59
B-1348 Louvain-la-Neuve Belgium fax: 010/ 47 34 52



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