NEB讨论

冰海里的一条鱼

SYSTEM = Al2O3
# Startparameter for this Run:
#  NWRITE = 2         !  how much will be written to the file OUTCAR ('verbosity flag')verbosity write-flag
   ISTART = 0         !  0-new 1-cont 2-samecut job,/if WAVECAR exists 1 restart with constant energy cut-off'/2 restart with constant basis set': Continuation job -- read wave functions from the file WAVECAR
#  ISPIN  = 2         !  1-no, 2-yes
   INIWAV = 1         !  0-jellium WF; 1-random numbers (recomm.)
   ICHARG = 2         !  ISTART = 0 2, else 0
#  WEIMIN = 0.001     !  for dynamic calculation IBRION >=0/for static calculation IBRION =-1
   dynamic:
  LPLANE = .TRUE.
  NPAR = 8
#  Electronic Relaxation
   ENCUT = 350        !  Ecut (eV)
   PREC = High    !  precission: #Low for MD/Medium for optimization/Accurate for TS and frequence
   EDIFF = 1.E-05     !  stopping-criterion for electronic upd.
   LREAL = Auto       !  .FALSE. projection done in reciprocal space/.TRUE. real space/On or O real space, projection operators re-optimized/Auto real space,fuly auto opti of projection operators  no user interference required
   NELMIN = 5         !  the minimum number of electronic SC steps
#  NELM = 150         !  max. # of electronic SC steps
#  NELMDL = 10        !  # of non-consistent steps at the beggining:>0 or 0MP broadening in eV -4 tet -1-fermi 0-gauss
   SIGMA = 0.2        !  
#  IWAVPR = 12        !  if  IBRION=0 (MD) 2,12/if IBRION=1,2 (relaxation)         1,11/else (static calculation) 0
# Ionic relaxation   
   EDIFFG = -0.05     !  break condition for the ionic relaxation loop/Default :EDIFF*10/negative ,will stop if all forces are smaller than [EDIFFG]
   IBRION = 2         !  ionic relax: -1:no move; 0-MD;1-Newton;2-CG;3-damped;4-?
   NSW = 400          !  steps for ionic update (def:0)
   ISIF = 2           !  calc.stress:0-no;1-tr;2-7 yes; 3-change vol.4-change shape
   POTIM = 0.3
# TS flags
   IMAGES = 8
#   NFREE = 2
   SPRING = -5
   ENERGY1 = -589.41939
   ENERGY2 = -590.393218
# Write flags
   LWAVE = .False.     !  write WAVECAR
   LCHARG = .False.    !  write CHGCAR and CHG
   LVTOT = .False.     !  write the local potential LOCPOT
   LELF = .False.      !create ELFCAR file
   LORBIT = .F.        !create PROOUT
# Others
#  APACO = 10.0       !distance for P.C.
   AMIX = 0.2
   BMIX = 0.0001
   AMIX_MAG = 0.8
   BMIX_MAG = 0.0001



用VASP做NBE计算，主要有这几个参数：
image=N, 初态与末态之间的image个数，SPRING=弹性恢复系数，用默认值-5就可以了，单位是ev/A^2，IBRION=1或3。在当前工作目录下要建N+2个子目录00，01，...，N+1.每个目录包括一个POSCAR，初态,末态的POSCAR分别放在00，N+1目录下面。中间的N个POSCAR需要在初态和末态之间通过线性插值得到。
VASP手册有Elastic band method这个小节。
对neb,取IBRION2，计算完neb 之后，IBRION取1结构优化，然后计算频率验证
NEB计算时，应该也是在算通过线性插值得到的中间态IMAGE的结构优化 那算完之后还要做IBRION=1的结构优化



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