Dear all,
I am doing some phonon calculations at the gamma point for a system of 8 atoms
. In the scf calculations I used an ultrasoft pseudopotential so I chose my
ecutrho= 8* ecutwfc and also in the ph.x calculations tr2_ph was set to 1
*10^(-19) but I still get that the three first values of the frequencies are
negative. Does this confirm the instability of the system?
SCF INPUT:
&system ibrav=0, celldm(1)= 9.008277, nat=8, ntyp= 2, ecutwfc
=32, ecutrho=256, occupations='smearing', smearing='mv',
degauss=0.02
/ &electrons conv_thr=1.D-6, mixing_beta=0.3D0, mixing_mode='plain',
diago_david_ndim=2,.....etc
PH INPUT:
&inputph
tr2_ph=1.0d-19,prefix='Graphyne',fildvscf='Graphydvscf',recover=.true.,trans=.true.,amass(1)=12.0107,amass(2)=1.00794,outdir='/home_cluster/fis718/eliemouj/espresso-4.3.2/Graphyne/GRAPHYNEDIR/',fildyn='Graphy.dynG'
/0.0 0.0 0.0
The output i got is :
omega( 1) = -11.303890 [THz] = -377.057178 [cm-1] omega( 2) =
-11.228798 [THz] = -374.552397 [cm-1] omega( 3) = -1.493780 [THz] =
-49.827127 [cm-1] omega( 4) = 1.499866 [THz] = 50.030148
[cm-1] omega( 5) = 2.192955 [THz] = 73.149113 [cm-1] omega(
6) = 11.690342 [THz] = 389.947822 [cm-1].......
Thanks for the help
Elie MouhaesUniversity of NottinghamNG7 2RD
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