[Thermo_pw-forum] Elastic constants at finite pressures using mur_lc_elastic_constants

[Sarah Arveson]

Hi all,

I am struggling to calculate the elastic constants at finite pressures and wonder if I am missing a crucial flag. The pressure is being read by the program, as the densities are correctly updated in the output file, but for any given pressure, only the equilibrium 0 pressure tensors are printed. (Resulting in incorrect sound speeds, etc.) Any advice would be greatly appreciated!

Here are my inputs for an example of B1 MgO at a pressure of 1375.5 kbar corresponding to a previously calculated corresponding lattice parameter of 7 a.u.:

 ********* thermo_control *********
 &INPUT_THERMO
  what='mur_lc_elastic_constants',
  pressure=1375.5
 /

 ********* pw.mgo.scf.in *********
 &CONTROL
    calculation = 'scf'
    restart_mode='from_scratch',
    prefix='MgO',
    tstress = .TRUE.,

    ! Note: MgO B1 (rocksalt) structure

     pseudo_dir = '../../pseudo',
     outdir     = 'output', 
 /

 &SYSTEM    
    ibrav = 2,
    celldm(1) = 7,
    nat =  2,
    ntyp = 2,
    ecutwfc = 44.0, 
 /
 
 &ELECTRONS
    conv_thr = 1.0d-8
 /

ATOMIC_SPECIES
   Mg  24.3050  Mg.pz-n-vbc.UPF
   O   15.9994  O.pz-rrkjus.UPF

ATOMIC_POSITIONS alat
   Mg 0.0 0.0 0.0 
   O  0.5 0.5 0.5 

K_POINTS automatic
   4 4 4  1 1 1

******************
Thanks in advance,
Sarah
-------------------------------------------------
Sarah M. Arveson
PhD Candidate, Yale University
Dept. of Earth and Planetary Sciences
sarah.arveson at gmail.com





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