I am relaxing the SrCrO3/SrTiO3 1:1 superlattice. I start with the structure of Cm space group(got it from FINDSYM with tolerance 1e-5, which is the tolerance of VASP). But VASP did not recognize this symmetry, and report a P1 symmetry. This leads to a CONTCAR of P1 space group. How does this happen??
The following is part of the OUTCAR:
Code: Select all
?Subroutine?GETGRP?returns:?Found??1?space?group?operations
?(whereof??1?operations?were?pure?point?group?operations)
?out?of?a?pool?of?16?trial?point?group?operations.
The?static?configuration?has?the?point?symmetry?C_1?.
Analysis?of?symmetry?for?dynamics?(positions?and?initial?velocities):
?Subroutine?DYNSYM?returns:?Found??1?space?group?operations
?(whereof??1?operations?were?pure?point?group?operations)
?out?of?a?pool?of??1?trial?space?group?operations
?(whereof??1?operations?were?pure?point?group?operations)
?and?found?also?????1?'primitive'?translations
The?dynamic?configuration?has?the?point?symmetry?C_1?.
Analysis?of?magnetic?symmetry:
?Subroutine?MAGSYM?returns:?Found??1?space?group?operations
?(whereof??1?operations?were?pure?point?group?operations)
?out?of?a?pool?of??1?trial?space?group?operations
?(whereof??1?operations?were?pure?point?group?operations)
?and?found?also?????1?'primitive'?translations
The?magnetic?configuration?has?the?point?symmetry?C_1?.
The POSCAR:
Code: Select all
SCO???????????????????#system?name
???3.84900000000000
1.00?-1.00?0
1.00?1.00?0
0?0?1.994
Sr?Cr?Ti?O
4?2?2?12
Direct
?-0.00000900?0.49999100?0.24999500
?0.50000900?0.00000900?0.25000500
?0.50000900?0.00000900?0.75000500
?-0.00000900?0.49999100?0.74999500
?0.00000000?0.00000000?0.00000000
?0.50000000?0.50000000?0.00000000
?0.00000000?0.00000000?0.50000000
?0.50000000?0.50000000?0.50000000
?0.00001200?-0.00001200?0.25000000
?0.00001200?-0.00001200?0.75000000
?0.22484600?0.72484600?0.49999850
?0.25000000?0.25000000?0.00000000
?0.25000000?0.75000000?0.00000000
?0.27516800?0.22483200?0.50000000
?0.49998800?0.50001200?0.75000000
?0.49998800?0.50001200?0.25000000
?0.72483200?0.77516800?0.50000000
?0.75000000?0.25000000?0.00000000
?0.75000000?0.75000000?0.00000000
?0.77515400?0.27515400?0.50000150
In another case, a initial structure also with Cm(tested by FINDSYM with 1e-5 tolerance) was recognized.
symmetry part of OUTCAR:
Code: Select all
?Subroutine?GETGRP?returns:?Found??2?space?group?operations
?(whereof??1?operations?were?pure?point?group?operations)
?out?of?a?pool?of?16?trial?point?group?operations.
The?static?configuration?has?the?point?symmetry?C_1?.
?The?point?group?associated?with?its?full?space?group?is?C_1h.
Analysis?of?symmetry?for?dynamics?(positions?and?initial?velocities):
?Subroutine?DYNSYM?returns:?Found??2?space?group?operations
?(whereof??1?operations?were?pure?point?group?operations)
?out?of?a?pool?of??2?trial?space?group?operations
?(whereof??1?operations?were?pure?point?group?operations)
?and?found?also?????1?'primitive'?translations
The?dynamic?configuration?has?the?point?symmetry?C_1?.
?The?point?group?associated?with?its?full?space?group?is?C_1h.
Analysis?of?magnetic?symmetry:
?Subroutine?MAGSYM?returns:?Found??2?space?group?operations
?(whereof??1?operations?were?pure?point?group?operations)
?out?of?a?pool?of??2?trial?space?group?operations
?(whereof??1?operations?were?pure?point?group?operations)
?and?found?also?????1?'primitive'?translations
The?magnetic?configuration?has?the?point?symmetry?C_1?.
?The?point?group?associated?with?its?full?space?group?is?C_1h.
Thus the symmetry of CONTCAR remained in Cm.
POSCAR of this case:
Code: Select all
SCO???????????????????#system?nam
???3.84900000000000
1.01?-1.01?0
1.01?1.01?0
0?0?1.984
Sr?Cr?Ti?O
4?2?2?12
Direct
?0.00001500?0.50001500?0.25000250
?0.00001500?0.50001500?0.75000250
?0.49998500?-0.00001500?0.74999750
?0.49998500?-0.00001500?0.24999750
?0.00000000?0.00000000?0.00000000
?0.50000000?0.50000000?0.00000000
?0.00000000?0.00000000?0.50000000
?0.50000000?0.50000000?0.50000000
?0.00000000?0.00000000?0.25000000
?0.00000000?0.00000000?0.75000000
?0.22987000?0.72987000?0.50000000
?0.25000000?0.25000000?0.00000000
?0.25000000?0.75000000?0.00000000
?0.27013000?0.22987000?0.50000000
?0.50000000?0.50000000?0.25000000
?0.50000000?0.50000000?0.75000000
?0.72987000?0.77013000?0.50000000
?0.75000000?0.25000000?0.00000000
?0.75000000?0.75000000?0.00000000
?0.77013000?0.27013000?0.50000000
Finally, these two have the same INCAR:
Code: Select all
SYSTEM?=?SCO
NWRITE?=?2
PREC???=?Accurate
ADDGRID?=?.TRUE.
ENCUT??=?500
EDIFF??=?1e-07
ISMEAR?=?0
SIGMA??=?0.05
LREAL=?.FALSE.
LASPH?=?.TRUE.?
NSW????=100?
NPAR?=?4
LPLANE?=?.TRUE.
LSCALU?=?.FALSE.
IBRION?=?2?
EDIFFG?=?-0.005
ISIF???=3
LORBIT?=?11
ISPIN=2
MAGMOM=?4*0?2?-2?14*0
LMAXMIX?=?4
VOSKOWN?=?1
LDAU?=?.TRUE.
LDAUTYPE?=?2
LDAUL?=?-1??2?-1?-1
LDAUU?=??0?2.5??0?0
LDAUJ?=??0?1.0?0?0
Looking forward for your replies!!!
Thanks,
Yuanjun
