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虫号: 801403
注册: 2009-06-30
性别: GG
专业: 金属材料的微观结构

[交流] 【求助】Ni的声子计算

我想计算Ni的声子谱。
第一步，先做了结构优化计算，输入文件如下：

# Ni fcc structure with two atoms per unit cell

#Ni is a ferromagnatic material
#spin definition
nsppol  2
nspden  2
spinat 0.0 0.0 4.0

prtdos 1
prtden 1

#Structure optimize
optcell  1
ionmov 2
ntime 15
dilatmx  1.05
tolmxf 1.0e-6
ecutsm 0.5

#######################################################
#Common data
acell 3*6.65184
rprim 0.0 0.5  0.5
      0.5 0.0  0.5
      0.5 0.5  0.0

ntypat 1
znucl 28

natom 1
typat 1

xred    0.0  0.0  0.0


ixc    11

occopt 3
tsmear 0.01
nband 10

kptopt 1
ngkpt 8 8 8
nshiftk  4
shiftk 0.5 0.5 0.5
      0.5 0.0 0.0
      0.0 0.5 0.0
      0.0 0.0 0.5

ecut    60.0
tolvrs 1.0d-18
iscf    5
nstep 70

diemac 12
计算得到的结果是：acell=6.73,查阅文献的结果是：6.65.
下面计算声子，
第一步，先做了，GS 计算,输入文件是：

# Ni fcc structure with two atoms per unit cell

#Ni is a ferromagnatic material
#spin definition
nsppol  2
nspden  2
spinat 0.0 0.0 4.0

prtdos 1
prtden 1

#Structure optimize
#optcell  1
#ionmov 2
#ntime 15
#dilatmx  1.05
#tolmxf 1.0e-6
ecutsm 0.5

#######################################################
#Common data
acell 3*6.65
rprim 0.0 0.5  0.5
      0.5 0.0  0.5
      0.5 0.5  0.0

ntypat 1
znucl 28

natom 1
typat 1

xred    0.0  0.0  0.0


ixc    11

occopt 3
tsmear 0.01
nband 10

kptopt 1
ngkpt 8 8 8
nshiftk  4
shiftk 0.5 0.5 0.5
      0.5 0.0 0.0
      0.0 0.5 0.0
      0.0 0.0 0.5

ecut    50
tolvrs 1.0d-18
iscf    5
nstep 70

diemac 12
计算得到WFK文件，以上两步计算都没有问题，no warning and no comment.
第二步计算Gamma点的声子。
输入文件如下，

# Crystalline Ni : computation of the second drivative of the total energy
#

#Ni is a ferromagnatic material
#spin definition
  nsppol 2
  nspden 2
  spinat 0.0  0.0  4.0

#Response-function calculatio, with q=0
  rfphon 1          # Will consider phonon-type perturbation
rfatpol 1 1       # all the  atoms wiil be displaced
rfdir 1 1 1       # Along the first reduced coordinate axis
nqpt 1          # One wavevector is to be considered
   qpt 0 0 0       # This wavevector is q=0 (Gamma)
  kptopt 2          # Automatic generation of k points, taking
                     # into account the time-reversal symmetry only
  tolvrs 1.0d-8    # SCF stopping criterion
iscf 5          # Self-consistent calculation, using algorithm 5
  irdwfk 1          # Read the ground-state wavefunctions

#########################################################################
#common input variables

#Definition of the unit cell
acell 3*6.65
rprim  0.0  0.5  0.5 # In lessons 1 and 2, these primitive vectors
   0.5  0.0  0.5 # (to be scaled by acell) were 1 0 0  0 1 0  0 0 1
   0.5  0.5  0.0 # that is, the default.

#Definition of the atom types
ntypat 1       # There is only one type of atom
znucl  28       # The keyword "znucl" refers to the atomic number of the
               # possible type(s) of atom. The pseudopotential(s)
               # mentioned in the "files" file must correspond
               # to the type(s) of atom. Here, the only type is Silicon.


#Definition of the atoms
natom 1          # There are two atoms
typat 1          # They both are of type 1, that is, Silicon.
xred             # This keyword indicate that the location of the atoms
               # will follow, one triplet of number for each atom
0.0  0.0  0.0  # Triplet giving the REDUCED coordinate of atom 1.
               # Triplet giving the REDUCED coordinate of atom 2.
               # Note the use of fractions (remember the limited
               # interpreter capabilities of ABINIT)

#Definition of the planewave basis set
ecut  50.0       # Maximal kinetic energy cut-off, in Hartree

#Definition of the k-point grid

ngkpt 8 8 8       # This is a 8x8x8 grid based on the primitive vectors
nshiftk 4       # of the reciprocal space (that form a BCC lattice !),
               # repeated four times, with different shifts :
shiftk 0.5 0.5 0.5
   0.5 0.0 0.0
   0.0 0.5 0.0
   0.0 0.0 0.5
               # In cartesian coordinates, this grid is simple cubic, and
               # actually corresponds to the
               # so-called 4x4x4 Monkhorst-Pack grid

ixc 11


occopt 3
tsmear 0.05
nband  10
#Definition of the SCF procedure
nstep  80       # Maximal number of SCF cycles


diemac 12.0       # Although this is not mandatory, it is worth to
               # precondition the SCF cycle. The model dielectric
               # function used as the standard preconditioner
               # is described in the "dielng" input variable section.
               # Here, we follow the prescription for bulk silicon.
问题就来了，得不到合理的结果，
而且log中有一大堆这样的WARNING:
cgwf3.F90:701:WARNING
New trial energy at line 4 = -8.174248E+02
is higher than former: -8.174248E+02
得到Gamma点声子竟然为：
Phonon wavevector (reduced coordinates) : 0.00000 0.00000 0.00000
Phonon energies in Hartree :
-3.212615E-03 -3.212615E-03 -3.212615E-03
Phonon frequencies in cm-1 :
- -7.050876E+02 -7.050876E+02 -7.050876E+02
有哪位达人能够帮我啊？告诉我问题出在哪里？
计算中所使用的赝势，可以在这里下载： http://www.sas.upenn.edu/rappegroup/htd ... p_gga.html

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