24小时热门版块排行榜

返回列表

当前只显示满足指定条件的回帖，点击这里查看本话题的所有回帖

yy08

木虫 (著名写手)

PHD

应助: 0 (幼儿园)
金币: 7246.1
散金: 8
红花: 1
帖子: 1455
在线: 161.4小时
虫号: 472942
注册: 2007-12-05
性别: GG
专业: 无机非金属类光电信息与功

[求助] 关于ABINIT计算四方结构弹性常数不收敛的问题

本人用ABINIT重复PRB（ 73, 245217 2006）一文章中一个四方结构的弹性常数，运行telast_2.fiels这一步的时候，set 1（Initial self-consistent run）很快收敛，但是从set 2开始就不收敛了。输入卡中的iscf的设置尝试了3、5、7等值，而且用了不同的赝势都进行了测试，都没能收敛。输入卡telast_2.in内容如下：
ndtset 3
# Set 1 : Initial self-consistent run
iscf1 7
  kptopt1 1
  tolvrs1 1.0d-18  #need excellent convergence of GS quantities for RF runs
# Set 2 : Calculate the ddk wf's - needed for piezoelectric tensor and
#       Born effective charges in dataset 3
  getwfk2  -1
iscf2  -3       #this option is needed for ddk
  kptopt2 2       #use time-reversal symmetry only for k points
nqpt2 1       #one wave vector will be specified
   qpt2 0 0 0 #need to specify gamma point
  rfelfd2 2       #set for ddk wf's only
rfdir2 1 1 1 #full set of directions needed
# rfdir2 1 0 0
  tolwfr2 1.0d-16  #only wf convergence can be monitored here
# Set 3 : response-function calculations for all needed perturbations
  getddk3  -1
  getwfk3  -2
iscf3 7
  kptopt3 2       #use time-reversal symmetry only for k points
nqpt3 1
   qpt3 0 0 0
  rfphon3 1       #do atomic displacement perturbation
rfatpol3 1 8    #do for all atoms
  rfstrs3 3       #do strain perturbation
rfdir3 1 1 1 #the full set of directions is needed
# rfdir3 1 0 0
tolvrs3 1.0d-10  #need reasonable convergence of 1st-order quantities
#Common input data
# acell  COPY RELAXED RESULT FROM PREVIOUS CALCULATION
# Here is a default value, for automatic testing : suppress it and fill the previous line
  acell  10.274  10.274  20.250
#  rprim sqrt(0.75)  0.5  0.0 #hexagonal primitive vectors must be
#       -sqrt(0.75)  0.5  0.0 #specified with high accuracy to be
#       0.0       0.0  1.0 #sure that the symmetry is recognized
                              #and preserved in the optimization
                              #process
  angdeg  90 90 90
  spgroup 122
  brvltt -1
  chkprim 0
#Definition of the atom types and atoms
  ntypat 3
  znucl 48 32 33
  natom 8
  typat 1  2  3
#Starting approximation for atomic positions in REDUCED coordinates
#based on ideal tetrahedral bond angles
# xred  COPY RELAXED RESULT FROM PREVIOUS CALCULATION
# Here is a set of default values, for automatic testing : suppress it and fill the previous line
  natrd  3
  xred  0.0 0.0 0.0
      0.0 0.0 0.5
      0.27 0.25 0.125
#Gives the number of bands, explicitely (do not take the default)
  nband 30
#Definition of the plane wave basis set
ecut 45.0          # Maximum kinetic energy cutoff (Hartree)
ecutsm 0.5
#Definition of the k-point grid
kptopt 1             # Use symmetry and treat only inequivalent points
ngkpt 4 4 4       # 4x4x4 Monkhorst-Pack grid
nshiftk 1             # Use one copy of grid only (default)
shiftk 0.0 0.0 0.0
#Definition of the self-consistency procedure
diemac 12.0          # Model dielectric preconditioner
iscf 7             # Use conjugate-gradient SCF cycle
nstep 4000          # Maxiumum number of SCF iterations
计算输出部分内容如下：
   iter 2DEtotal(Ha)       deltaE(Ha) residm vres2
-ETOT  1  -45.484530143467    -4.548E+01 6.521E-01 0.000E+00
ETOT  2  -45.795933477839    -3.114E-01 1.429E-01 0.000E+00
ETOT  3  -45.815094454386    -1.916E-02 1.606E-02 0.000E+00
ETOT  4  -45.817797043619    -2.703E-03 7.576E-02 0.000E+00
ETOT  5  -45.818278447453    -4.814E-04 1.092E-02 0.000E+00
ETOT  6  -45.818372532096    -9.408E-05 6.982E-02 0.000E+00
ETOT  7  -45.818391953073    -1.942E-05 9.658E-03 0.000E+00
ETOT  8  -45.818396113087    -4.160E-06 6.921E-02 0.000E+00
ETOT  9  -45.818397027188    -9.141E-07 9.109E-03 0.000E+00
ETOT 10  -45.818397231562    -2.044E-07 6.907E-02 0.000E+00
ETOT 11  -45.818397277798    -4.624E-08 8.879E-03 0.000E+00
ETOT 12  -45.818397288342    -1.054E-08 6.898E-02 0.000E+00
residm这一列进入了一个死循环，所以 set2中的tolwfr2（1.0d-16）一直不能收敛。请各位老师指点一下，谢谢大家！

回复此楼