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[求助]
VASP MD 得到 amorphous结构已有1人参与
大家好。我想利用VASP跑分子动力学模拟得到amorphous结构。思路大概是从crystalline phase起先melt再quench。有一个问题是,amorphous phase的密度一般比crystalline phase密度要低,所以其晶格常数要大一些。如果始终用NVT ensemble的话晶格常数不会改变,这样得到的结构不太合理,因为得到的amorphous 结构密度和crystalline phase一样,会存在很大 residual stress。所以我试着用NpT ensemble (ISIF=3),保持压强为一个大气压,期望晶格常数会有所增加,得到合理的结构。现在问题是,NpT MD时候晶格常数一直不变,请问怎么回事?
INCAR file:
# General parameters for this run
System= SnO2
NCORE = 12
# Electronic specification
PREC = Normal ! standard precision, we recomend the use of PREC = Normal
ENCUT = 150 ! cutoff should be set manually, smaller if ultra-large supercell
ISMEAR= 0
SIGMA = 0.01
LREAL = Auto ! Real space to spped up for large molecular dynamics runs
ALGO = Very Fast ! For large molecular dynamics runs
NELMIN= 4 ! Set minimum steps of electronic optimization
EDIFF = 1E-3 ! Do not use default, too much drift
# MD related
# NpT
ISYM = 0 ! strongly recommened for MD, no symmertry
IBRION= 0 ! molecular dynamics
NSW = 7500 ! 7500 steps
POTIM = 2 ! timestep 2 fs
# SMASS = -1 ! Nose Hoover thermostat
ISIF = 3
MDALGO= 3 !
TEBEG = 3000
TEEND = 300 ! temperature
PSTRESS= 0.001
# Output control
NBLOCK= 50 ! XDATCAR updated every 50 steps
NWRITE = 0 ! For MD, use NWRITE = 0 or NWRITE = 1
LCHARG = .FALSE.
LWAVE = .FALSE. |
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