[Thermo_pw-forum] The computational workload is overwhelming

[wuan19992022]

Dear community,



When I used thermo_pw to calculate the elastic constants, I encountered a problem of huge amount of calculation.I calculated the orthorhombic crystal, which has nine independent elastic constants.Then I see fields like this in the out file：“ It requires nine strains for a total of 54 scf calculations ”，and " The celldm of the  125 unperturbed geometries are:" and " Number of geometries to compute: 6750, Phonons computed in:  6750 geometries".


This amount of calculation is really huge. Is there any way to reduce the amount of calculation? Or is it that this number was pre-set ? Is it unalterable ?


input file:
&CONTROL
  calculation='scf', pseudo_dir='./', outdir='./', verbosity='high',
  tprnfor=.true., tstress=.true., forc_conv_thr=1.0d-4, nstep=100,
/
&SYSTEM
  ibrav= 8, nat= 4, ntyp= 1, celldm(1)=8.882639, celldm(2)=0.782693, celldm(3)=8.509751, 
  occupations = 'smearing', smearing = 'gaussian', degauss = 1.0d-5,
  ecutwfc = 50, ecutrho = 300,
/
&ELECTRONS
  conv_thr = 1.0d-9
  mixing_beta = 0.1d0
  mixing_ndim = 12
  electron_maxstep = 300
/
&IONS
  ion_dynamics ='bfgs'
/
ATOMIC_SPECIES
  As 74.9216 As.pbe-dn-kjpaw_psl.1.0.0.UPF
ATOMIC_POSITIONS (crystal)
  As  0.2480337522  0.2500000000  0.2200282295
  As  0.6092512478  0.7500000000  0.2200311969
  As  0.1092512478  0.2500000000  0.2799688031
  As  0.7480337522  0.7500000000  0.2799717705
K_POINTS {automatic}
  5 6 1 0 0 0


thermo_control file :
&INPUT_THERMO
   what='elastic_constants_geo',
   frozen_ions=.FALSE.
   elastic_algorithm='energy'
   use_free_energy=.TRUE.
   lmurn=.FALSE.
   deltat=5.
 /


Kind regards and thanks in advance.


--
Wu an
Department of Mechanics, College of Mathematics and Physics
University of Science and Technology Beijing

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