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各位老师好，最近在做CO2分子吸附在石墨烯表面的静态计算，在结构优化时，需要将小分子CO2也放入晶胞中优化。开始时，将手动搭建CO2放入10*10*10的正方体晶胞中，后来听从别人的建议，将手动搭建CO2分子放入12*12*16，夹角为90° 90° 120°的与石墨烯晶胞大小相同的晶胞进行优化。两者除晶胞不同之外，其他都相同，计算结果显示，二者都达到收敛精度，但其绝对能量一个为-22.9763531 eV（正方体晶胞），-15.88446113 eV（石墨烯晶胞），因此给接下来的吸附能计算造成很大的不同，不知为何，特来求教。
附上我所用的INCAR文件
SYSTEM = V
ISTART = 1 # whether or not to read the WAVECAR file.
ICHARG = 1 # how VASP constructs the initial charge density.
LWAVE = .TRUE. # whether the wavefunctions are written to the WAVECAR file
LCHARG = .TRUE. # LCHARG determines whether the charge densities (files CHGCAR and CHG) are written.
LVTOT = .FALSE. # whether the total local potential is written to the LOCPOT file
LVHAR = .FALSE. # whether the electrostatic potential is written to the LOCPOT file
LELF = .FALSE. # whether to create an ELFCAR file or not.
# LORBIT = 11 # determines whether the PROCAR or PROOUT files are written.
#### Electronic Relaxation ####
ENCUT = 400 # cutoff energy for the planewave basis set in eV
ISMEAR = 0 # how the partial occupancies are set for each orbital.
SIGMA = 0.05 # the width of the smearing in eV.
EDIFF = 1E-6 # global break condition for the electronic SC-loop
NELMIN = 5 # specifies the minimum number of electronic SCF steps.
NELM = 300 # maximum number of electronic SC (selfconsistency) steps
GGA = PE # type of generalized-gradient-approximation one wishes to use.
LREAL = Auto # whether the projection operators are evaluated in real-space or in reciprocal space.
LDIPOL = .TRUE.
IDIPOL = 3 # add dipole correction
ISYM = 0 # determines the way VASP treats symmetry.
ALGO = Normal # electronic minimisation algorithm
PREC = Normal # specifies the "precision"-mode
ADDGRID = .TRUE. # whether an additional support grid is used for the evaluation of the augmentation charges
# AMIX = 0.2
# BMIX = 0.0001
# AMIX_MAG = 0.8
# BMIX_MAG = 0.0001
# MAXMIXÃa |
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发表于 Post on 2022-3-4 22:02:23
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