structural optimization becomes unstable

Total energy, geometry optimization, DFT+U, spin....

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raul_l
Posts: 74
Joined: Sun Jan 08, 2012 7:45 pm

structural optimization becomes unstable

Post by raul_l » Sun Jun 08, 2014 9:45 pm

I tried to do structural optimization with BaWO4,

Code: Select all

# BaWO4

ndtset 2

###################
# Crystal structure
###################

scalecart 2*5.6134 12.720 angstrom
rprim
 -0.5  0.5  0.5
  0.5 -0.5  0.5
  0.5  0.5 -0.5
ntypat 3
znucl 56 74 8
natom 12
typat      1  2  3  3  1  2  3  3  3  3  3  3
             xred      5.0000000000E-01  5.0000000000E-01  0.0000000000E+00
                       0.0000000000E+00  0.0000000000E+00  0.0000000000E+00
                       2.0080000000E-01  3.1130000000E-01  3.5590000000E-01
                       9.5540000000E-01  8.4490000000E-01  6.4410000000E-01
                       2.5000000000E-01  7.5000000000E-01  5.0000000000E-01
                       7.5000000000E-01  2.5000000000E-01  5.0000000000E-01
                       6.1300000000E-02  2.0540000000E-01  6.1050000000E-01
                       5.9490000000E-01  4.5080000000E-01  3.8950000000E-01
                       5.4920000000E-01  9.3870000000E-01  1.4410000000E-01
                       7.9460000000E-01  4.0510000000E-01  8.5590000000E-01
                       6.8870000000E-01  4.4600000000E-02  8.8950000000E-01
                       1.5510000000E-01  7.9920000000E-01  1.1050000000E-01

###############
# BZS and bands
###############

ngkpt 3*4
shiftk 3*0.5
nbdbuf 5
nband 53

####################
# Molecular dynamics
####################

ionmov 3
ecutsm2 0.5

optcell1 0
optcell2 2

#################
# Cutoff energies
#################

ecut 22
pawecutdg 60

############
# Tolerances
############

toldff 1.0d-6
tolmxf 1.0d-5
dilatmx2 1.05
nstep 50
ntime 50

###############
# Data handling
###############

prtwf 0
prtden 0
getxred -1

######
# Misc
######

diemac 4

but for some reason the procedure doesn't converge. Here is 'grep tolmxf log':

Code: Select all

  max grad (force/stress) = 8.7684E-03 > tolmxf= 1.0000E-05 ha/bohr (free atoms)
  max grad (force/stress) = 3.7869E-03 > tolmxf= 1.0000E-05 ha/bohr (free atoms)
  max grad (force/stress) = 4.7618E-04 > tolmxf= 1.0000E-05 ha/bohr (free atoms)
  max grad (force/stress) = 4.9138E-04 > tolmxf= 1.0000E-05 ha/bohr (free atoms)
  max grad (force/stress) = 9.3201E-03 > tolmxf= 1.0000E-05 ha/bohr (free atoms)
  max grad (force/stress) = 9.5312E-02 > tolmxf= 1.0000E-05 ha/bohr (free atoms)
  max grad (force/stress) = 2.6146E-01 > tolmxf= 1.0000E-05 ha/bohr (free atoms)
  max grad (force/stress) = 7.8148E-01 > tolmxf= 1.0000E-05 ha/bohr (free atoms)
  max grad (force/stress) = 1.5120E+00 > tolmxf= 1.0000E-05 ha/bohr (free atoms)

Initially, the convergence seems promising, but then it worsens until the calculation stops with an error. What could cause such behavior? I tried changing several input paramaters and different PAW datasets but nothing helps. Also, I should mention that there are no problems with CaWO4, for which I use an almost identical input. I have attached the output files.
Attachments
log.out
log
(820.35 KiB) Downloaded 284 times
scf.outC.out
out
(112.35 KiB) Downloaded 222 times
Raul Laasner
Netherlands Institute for Space Research

raul_l
Posts: 74
Joined: Sun Jan 08, 2012 7:45 pm

Re: structural optimization becomes unstable

Post by raul_l » Tue Jun 10, 2014 7:15 pm

The problem seems to be related to using Intel compilers and the Intel MPI library. If I configure with either Intel compilers and MPICH or GNU compilers and Intel MPI then the calculation converges nicely. In all three cases the first 4 steps of optimization are identical.
Raul Laasner
Netherlands Institute for Space Research

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