Phonon dispersion using fix-phonon

Dear Lammps users and devs

I’m trying to use the “fix-phonon” to calculate the phonon dispersion for MoS2 Monolayer using a potential i’ve been developing using machine learning and DFT data. I was able to reproduce the phonon dispersion using lammps as a tool in a package called Alamode ( T. Tadano, Y. Gohda, and S. Tsuneyuki, J. Phys.: Condens. Matter 26 , 225402 (2014)) without problems at gamma

I’m having problems next gamma. the phonon dispersion explodes to negative values and positive values of order of >10^3 thz. If i include the option “-r” at “./phana” even if knowing I should not use it because I’m not including charges on my systems the problem of exploding values at gamma dissapear but I end up with highly unnacurate values for frequencies at Gamma.

I’m making simulations using 50x50x1 cell (7500 atoms total) and for timestep = 1 fs for 5000000 steps.

Here’s the input im using:

atom_style atomic
boundary p p p
velocity all create 300 35131 dist gaussian
group S type 1
group Mo type 2
pair_style aenet
pair_coeff * * v-1 S Mo good_phonon0.ann S Mo
timestep 0.001 #ps
thermo 500 # intervalo para mostrar output instantaneos.
neighbor 2.0 bin
neigh_modify every 3 delay 0 check yes
dump myDump all xyz 1000
dump_modify myDump element S Mo
fix 1 all langevin 300 300 0.1 73504 zero yes
fix 2 all nve
fix 3 all phonon 10 50000 1000000 mos2Phonon_lang nasr 50
run 5000000

thanks in advance for the help

For questions about the fix phonon and the phana tool, you better contact the developer of that functionality directly, e.g. at GitHub - lingtikong/phana

Does he also have a account here to?

I don’t know, and how should I. There are way over 10,000 users registered here. Many don’t configure their user profile. The best way to find out is to contact him directly.