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标题: 求助：关于用VASP加电场复现文献仍为物理吸附和电场单位换算相关问题 [打印本页]

作者
Author: liuxr 时间: 2022-8-25 10:59
标题: 求助：关于用VASP加电场复现文献仍为物理吸附和电场单位换算相关问题

各位老师好，本人重复用MS软件进行计算的文献《Electric field assistedactivation of CO2 over P-doped graphene: A DFT study》，其中提到在不加电场时CO2吸附在P掺杂的石墨烯表面为物理吸附，加入0.013 a.u.电场后可由物理吸附转变为化学吸附，如图所示：

本人用VASP进行相关计算的复现，在加入0.013 a.u.电场后，CO2分子仍为物理吸附状态下的直线型分子，如图所示。而找人用MS计算，发现可以得到和文献类似的结论。

现在我的问题有：

1、在使用该文献中，使用MS软件计算且单位为 a.u. ，而VASP中的电场强度的单位为 eV/Å。我又在博文https://blog.sciencenet.cn/blog-685489-951826.html中了解到，在MS的Dmol3 模块中1 a.u. = 51.36 V/A ，而在QE中1 a.u.=25.68 V/A 。由于不同软件1 a.u.对应的V/A的数值不同，那么在使用VASP计算中，1 a.u. = 51.423 V/A，1 V/A = 1 eV/Å这种单位换算可靠吗？可以将1 V/A 等同于1 eV/Å吗，依据是什么？

2、如果单位是可靠的，那么在我的计算过程中是否存在参数遗漏或是计算不合理的地方？

附上计算过程中使用的INCAR和CONCAR文件：

##### initial parameters I/O #####

SYSTEM = PC

NCORE = 14

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 WAVECARfile

LCHARG = .TRUE. # LCHARG determines whether the charge densities (filesCHGCAR and CHG) are written.

LVTOT = .FALSE. # whether the total local potential is written to theLOCPOT file

LVHAR = .FALSE. # whether the electrostatic potential is written to theLOCPOT file

LELF = .FALSE. # whether to create an ELFCAR file or not.

#### Electronic Relaxation ####

ENCUT = 500 # 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 touse.

LREAL = Auto # whether the projection operators are evaluated inreal-space or in reciprocal space.

LDIPOL = .TRUE.

IDIPOL = 3 # add dipole correction

EFIELD = -0.62 #controls the magnitude of the applied electric forcefield

DIPOL = 0.5 0.5 0.5 #specifies the center of the cell in direct latticecoordinates with respect to which the total dipole-moment in the cell iscalculated

ISYM = 0 # determines the way VASP treats symmetry.

ALGO = Normal # electronic minimisation algorithm

PREC = Normal # specifies the "precision"-mode

#### Geometry opt parameters ####

EDIFFG = -0.02 # EDIFFG defines the break condition for the ionicrelaxation loop.

IBRION = 2 # IBRION determines how the ions are updated and moved.

POTIM = 0.2 # POTIM sets the time step (MD) or step width scaling(ionic relaxations).

NSW = 1000 # maximum number of ionic steps.

ISIF = 2 # determines whether the stress tensor is calculated and whichprincipal degrees-of-freedom are allowed to change

IVDW = 11

作者
Author: dcrdys 时间: 2022-10-8 17:28
请问楼主电场换算单位解决了吗

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