electronic convergence problem in interface structure
Posted: Sat Jan 03, 2009 10:35 pm
Dear all,
I am trying to relax an interface structure and construct an UBER curve. I am experiencing problems in the electronic convergence of systems where the interface separation is larger than some value. For instance if I separate the surfaces 10 A apart the system can not find an electronic minimum. If surfaces are close to each oher for some extent there is no convergence problem.
My INCAR file is:
SYSTEM = interface
PREC = Accurate
ISTART = 0
NSW = 200
IBRION = 2
ISIF = 2
ENCUT = 600
ISMEAR =-5
EDIFF = 1E-5
ALGO = Fast
LREAL = Auto
EDIFFG = -0.05
NELMDL = -10
AMIX = 0.2
BMIX = 0.5
AMIX_MAG = 0.8
BMIX_MAG = 0.5
My OSZICAR is like
N E dE d eps ncg rms rms(c)
DAV: 1 0.186433837546E+04 0.18643E+04 -0.16507E+05 8064 0.149E+03
DAV: 2 -0.348350591605E+03 -0.22127E+04 -0.20443E+04 10384 0.277E+02
DAV: 3 -0.585344673172E+03 -0.23699E+03 -0.23460E+03 9488 0.936E+01
DAV: 4 -0.592542603986E+03 -0.71979E+01 -0.71669E+01 10080 0.176E+01
DAV: 5 -0.592965707665E+03 -0.42310E+00 -0.42278E+00 13680 0.377E+00
DAV: 6 -0.592974041311E+03 -0.83336E-02 -0.83267E-02 12496 0.475E-01
DAV: 7 -0.592974654421E+03 -0.61311E-03 -0.61275E-03 14192 0.954E-02
DAV: 8 -0.592974678099E+03 -0.23678E-04 -0.23647E-04 12032 0.182E-02
DAV: 9 -0.592974679976E+03 -0.18764E-05 -0.18725E-05 9120 0.460E-03
DAV: 10 -0.592974680161E+03 -0.18516E-06 -0.18385E-06 6624 0.203E-03 0.268E+01
RMM: 11 -0.600318682493E+03 -0.73440E+01 -0.10283E+01 8092 0.442E+00 0.225E+01
RMM: 12 -0.674701331012E+03 -0.74383E+02 -0.34431E+01 8375 0.299E+00 0.325E+01
RMM: 13 -0.727602908848E+03 -0.52902E+02 -0.40898E+01 8621 0.473E+00 0.348E+01
RMM: 14 -0.578049706543E+03 0.14955E+03 -0.13876E+01 8265 0.385E+00 0.131E+01
RMM: 15 -0.575588952525E+03 0.24608E+01 -0.58648E+00 8434 0.408E+00 0.626E+00
RMM: 16 -0.581221725609E+03 -0.56328E+01 -0.60518E-01 8762 0.101E+00 0.786E+00
RMM: 17 -0.574174375435E+03 0.70474E+01 -0.10299E+00 8450 0.133E+00 0.370E+00
RMM: 18 -0.573710099508E+03 0.46428E+00 -0.10641E+00 8422 0.114E+00 0.241E+00
RMM: 19 -0.573747326028E+03 -0.37227E-01 -0.22180E-01 9283 0.516E-01 0.195E+00
RMM: 20 -0.573697093043E+03 0.50233E-01 -0.71953E-02 8474 0.396E-01 0.123E+00
RMM: 21 -0.573649041301E+03 0.48052E-01 -0.69699E-02 8355 0.487E-01 0.704E-01
RMM: 22 -0.573628885562E+03 0.20156E-01 -0.57171E-02 8759 0.269E-01 0.294E-01
RMM: 23 -0.573624483742E+03 0.44018E-02 -0.29685E-02 8674 0.189E-01 0.182E-01
RMM: 24 -0.573625489104E+03 -0.10054E-02 -0.49084E-03 8578 0.692E-02 0.110E-01
RMM: 25 -0.573624070382E+03 0.14187E-02 -0.68175E-03 8372 0.686E-02 0.722E-02
RMM: 26 -0.573622389466E+03 0.16809E-02 -0.10098E-02 7811 0.286E-02 0.595E-02
RMM: 27 -0.573620236320E+03 0.21531E-02 -0.19777E-02 8082 0.404E-02 0.579E-02
RMM: 28 -0.573621567057E+03 -0.13307E-02 -0.38388E-02 6057 0.177E-02 0.531E-02
RMM: 29 -0.573622727155E+03 -0.11601E-02 -0.78197E-02 6539 0.194E-02 0.512E-02
RMM: 30 -0.573628995257E+03 -0.62681E-02 -0.16060E-01 5014 0.157E-02 0.505E-02
RMM: 31 -0.573640535991E+03 -0.11541E-01 -0.32256E-01 5736 0.227E-02 0.494E-02
RMM: 32 -0.573664978328E+03 -0.24442E-01 -0.65533E-01 5900 0.296E-02 0.472E-02
RMM: 33 -0.573701970743E+03 -0.36992E-01 -0.11534E+00 6251 0.379E-02 0.452E-02
RMM: 34 -0.573754161857E+03 -0.52191E-01 -0.18648E+00 5621 0.449E-02 0.445E-02
RMM: 35 -0.573805616446E+03 -0.51455E-01 -0.25949E+00 5861 0.538E-02 0.417E-02
RMM: 36 -0.573851000327E+03 -0.45384E-01 -0.32652E+00 4584 0.589E-02 0.406E-02
RMM: 37 -0.573889173576E+03 -0.38173E-01 -0.38008E+00 3630 0.640E-02 0.396E-02
RMM: 38 -0.573908723749E+03 -0.19550E-01 -0.42076E+00 4176 0.736E-02 0.391E-02
I increased NBAND, I increased NELMDL, I played with mixing tags (AMIX, BMIX, ...), but there was no improvement. I checked my structure several times. Even in some systems, VASP can decrease the forces below 0.05, but can not find an electronic minimum. I am using 18 kpoints with (10x10x1) grid. The system has 86 atoms and that k-point scheme is enough as I tested. It came to me a bit strange that there is problem in the systems where the interface separation is large.
I am looking forward to your suggestions about this problem.
Thanks in advance.
Fatih.
I am trying to relax an interface structure and construct an UBER curve. I am experiencing problems in the electronic convergence of systems where the interface separation is larger than some value. For instance if I separate the surfaces 10 A apart the system can not find an electronic minimum. If surfaces are close to each oher for some extent there is no convergence problem.
My INCAR file is:
SYSTEM = interface
PREC = Accurate
ISTART = 0
NSW = 200
IBRION = 2
ISIF = 2
ENCUT = 600
ISMEAR =-5
EDIFF = 1E-5
ALGO = Fast
LREAL = Auto
EDIFFG = -0.05
NELMDL = -10
AMIX = 0.2
BMIX = 0.5
AMIX_MAG = 0.8
BMIX_MAG = 0.5
My OSZICAR is like
N E dE d eps ncg rms rms(c)
DAV: 1 0.186433837546E+04 0.18643E+04 -0.16507E+05 8064 0.149E+03
DAV: 2 -0.348350591605E+03 -0.22127E+04 -0.20443E+04 10384 0.277E+02
DAV: 3 -0.585344673172E+03 -0.23699E+03 -0.23460E+03 9488 0.936E+01
DAV: 4 -0.592542603986E+03 -0.71979E+01 -0.71669E+01 10080 0.176E+01
DAV: 5 -0.592965707665E+03 -0.42310E+00 -0.42278E+00 13680 0.377E+00
DAV: 6 -0.592974041311E+03 -0.83336E-02 -0.83267E-02 12496 0.475E-01
DAV: 7 -0.592974654421E+03 -0.61311E-03 -0.61275E-03 14192 0.954E-02
DAV: 8 -0.592974678099E+03 -0.23678E-04 -0.23647E-04 12032 0.182E-02
DAV: 9 -0.592974679976E+03 -0.18764E-05 -0.18725E-05 9120 0.460E-03
DAV: 10 -0.592974680161E+03 -0.18516E-06 -0.18385E-06 6624 0.203E-03 0.268E+01
RMM: 11 -0.600318682493E+03 -0.73440E+01 -0.10283E+01 8092 0.442E+00 0.225E+01
RMM: 12 -0.674701331012E+03 -0.74383E+02 -0.34431E+01 8375 0.299E+00 0.325E+01
RMM: 13 -0.727602908848E+03 -0.52902E+02 -0.40898E+01 8621 0.473E+00 0.348E+01
RMM: 14 -0.578049706543E+03 0.14955E+03 -0.13876E+01 8265 0.385E+00 0.131E+01
RMM: 15 -0.575588952525E+03 0.24608E+01 -0.58648E+00 8434 0.408E+00 0.626E+00
RMM: 16 -0.581221725609E+03 -0.56328E+01 -0.60518E-01 8762 0.101E+00 0.786E+00
RMM: 17 -0.574174375435E+03 0.70474E+01 -0.10299E+00 8450 0.133E+00 0.370E+00
RMM: 18 -0.573710099508E+03 0.46428E+00 -0.10641E+00 8422 0.114E+00 0.241E+00
RMM: 19 -0.573747326028E+03 -0.37227E-01 -0.22180E-01 9283 0.516E-01 0.195E+00
RMM: 20 -0.573697093043E+03 0.50233E-01 -0.71953E-02 8474 0.396E-01 0.123E+00
RMM: 21 -0.573649041301E+03 0.48052E-01 -0.69699E-02 8355 0.487E-01 0.704E-01
RMM: 22 -0.573628885562E+03 0.20156E-01 -0.57171E-02 8759 0.269E-01 0.294E-01
RMM: 23 -0.573624483742E+03 0.44018E-02 -0.29685E-02 8674 0.189E-01 0.182E-01
RMM: 24 -0.573625489104E+03 -0.10054E-02 -0.49084E-03 8578 0.692E-02 0.110E-01
RMM: 25 -0.573624070382E+03 0.14187E-02 -0.68175E-03 8372 0.686E-02 0.722E-02
RMM: 26 -0.573622389466E+03 0.16809E-02 -0.10098E-02 7811 0.286E-02 0.595E-02
RMM: 27 -0.573620236320E+03 0.21531E-02 -0.19777E-02 8082 0.404E-02 0.579E-02
RMM: 28 -0.573621567057E+03 -0.13307E-02 -0.38388E-02 6057 0.177E-02 0.531E-02
RMM: 29 -0.573622727155E+03 -0.11601E-02 -0.78197E-02 6539 0.194E-02 0.512E-02
RMM: 30 -0.573628995257E+03 -0.62681E-02 -0.16060E-01 5014 0.157E-02 0.505E-02
RMM: 31 -0.573640535991E+03 -0.11541E-01 -0.32256E-01 5736 0.227E-02 0.494E-02
RMM: 32 -0.573664978328E+03 -0.24442E-01 -0.65533E-01 5900 0.296E-02 0.472E-02
RMM: 33 -0.573701970743E+03 -0.36992E-01 -0.11534E+00 6251 0.379E-02 0.452E-02
RMM: 34 -0.573754161857E+03 -0.52191E-01 -0.18648E+00 5621 0.449E-02 0.445E-02
RMM: 35 -0.573805616446E+03 -0.51455E-01 -0.25949E+00 5861 0.538E-02 0.417E-02
RMM: 36 -0.573851000327E+03 -0.45384E-01 -0.32652E+00 4584 0.589E-02 0.406E-02
RMM: 37 -0.573889173576E+03 -0.38173E-01 -0.38008E+00 3630 0.640E-02 0.396E-02
RMM: 38 -0.573908723749E+03 -0.19550E-01 -0.42076E+00 4176 0.736E-02 0.391E-02
I increased NBAND, I increased NELMDL, I played with mixing tags (AMIX, BMIX, ...), but there was no improvement. I checked my structure several times. Even in some systems, VASP can decrease the forces below 0.05, but can not find an electronic minimum. I am using 18 kpoints with (10x10x1) grid. The system has 86 atoms and that k-point scheme is enough as I tested. It came to me a bit strange that there is problem in the systems where the interface separation is large.
I am looking forward to your suggestions about this problem.
Thanks in advance.
Fatih.