BRMIX: old and new charge density differ warning for doping calculations
Posted: Thu Dec 21, 2023 3:56 pm
Hello,
I am trying to perform calculations with a slab geometry, using a material that is by default insulating. I want to explore the effect of uniform electron doping and I am doing so by changing the value of NELECT, and initially relaxing the internal positions for each value. However, for any value other than the default, uncharged value, I get a warning in the output file after about the fifth electronic iteration saying "BRMIX: very serious problems
the old and the new charge density differ
old charge density: 552.00000 new 553.00000"
However, after this warning the calculation continues and, as far as I can tell, converges perfectly fine. I have a pretty high k-mesh (17x6x1) for a 4.9 x 13.5 x 30 angstrom slab (last direction has 20 angstrom vacuum) and I'm using gaussian smearing with a fairly large sigma=0.1 (these are the things are saw in previous posts which would be carefully checked when trying to use doping with NELECT). Given this, and the following INCAR, I was wondering whether I can probably safely ignore the warning if the output seems reasonable, or if I need to change something to get rid of it? Thanks in advance.
ENCUT = 910.000000 #700*1.3 for relaxations
EDIFF = 1.00e-05
ISMEAR = 0
SIGMA=0.1
NELM=1000
ADDGRID=.TRUE.
LMAXMIX = 4
LORBIT = 11
NCORE = 18
LDAUPRINT=2
LDAUTYPE=2
LASPH = .TRUE.
LDAU = .TRUE.
LDAUL = 2 -1
LDAUU = 4.000 0.000
LDAUJ = 0.000 0.000
ISPIN=2
MAGMOM= 3 -3 -3 3 3 -3 3 -3 -3 -3 3 3 3 -3 3 -3 -3 -3 3 3 3 -3 3 -3 36*0
IDIPOL=3
NELECT=553 #adding one electron to system
ISIF=2
IBRION=1
EDIFFG=-0.01
NSW=2000
I am trying to perform calculations with a slab geometry, using a material that is by default insulating. I want to explore the effect of uniform electron doping and I am doing so by changing the value of NELECT, and initially relaxing the internal positions for each value. However, for any value other than the default, uncharged value, I get a warning in the output file after about the fifth electronic iteration saying "BRMIX: very serious problems
the old and the new charge density differ
old charge density: 552.00000 new 553.00000"
However, after this warning the calculation continues and, as far as I can tell, converges perfectly fine. I have a pretty high k-mesh (17x6x1) for a 4.9 x 13.5 x 30 angstrom slab (last direction has 20 angstrom vacuum) and I'm using gaussian smearing with a fairly large sigma=0.1 (these are the things are saw in previous posts which would be carefully checked when trying to use doping with NELECT). Given this, and the following INCAR, I was wondering whether I can probably safely ignore the warning if the output seems reasonable, or if I need to change something to get rid of it? Thanks in advance.
ENCUT = 910.000000 #700*1.3 for relaxations
EDIFF = 1.00e-05
ISMEAR = 0
SIGMA=0.1
NELM=1000
ADDGRID=.TRUE.
LMAXMIX = 4
LORBIT = 11
NCORE = 18
LDAUPRINT=2
LDAUTYPE=2
LASPH = .TRUE.
LDAU = .TRUE.
LDAUL = 2 -1
LDAUU = 4.000 0.000
LDAUJ = 0.000 0.000
ISPIN=2
MAGMOM= 3 -3 -3 3 3 -3 3 -3 -3 -3 3 3 3 -3 3 -3 -3 -3 3 3 3 -3 3 -3 36*0
IDIPOL=3
NELECT=553 #adding one electron to system
ISIF=2
IBRION=1
EDIFFG=-0.01
NSW=2000