[Pw_forum] help: the phonon calculation
yuhailin_79 at msn.com
Mon Aug 28 04:23:25 CEST 2006
I have some quesitons want to know. Can you tell me ? Thanks a lot!
1).Recently, I had calculated Ag3N which has the anti-ReO3 strucuture (i.e,
has the same structure with Cu3N,PRB 53,12648) by using CASTEP and found
it's mechnical stabel ( I find the elastic siffness coefficients of Ag3N
satisfy the generalized elastic stability criteria). But when I calculated
the phonon dispersion of Ag3N using PWSCF, I found there was a soft mode
along G-X direcition (i.e the phonon frequency is negative). For a negative
frequency appear, it means that the structure is not stable? If so, the
results of CASTEP and PWSCF is confict? This quesiton is still confuzed me
and I am eager to receive your reply. Thanks!
2). For f-electronic materials (such as Pt), for their lattice dynamics
properties, it is reasonable to calculate using PWSCF ?
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