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

Prettyswan

木虫 (小有名气)

应助: 0 (幼儿园)
金币: 2919
帖子: 145
在线: 59.7小时
虫号: 958555

[交流] 【求助成功】结构优化之前，结果比较好；结构优化之后，基态与文献报道不符

实验和文献中都证实了CaFe2As2低温基态为AFM1（我们自己命名，几种可能的此结构如下）

我发现如果直接使用实验值而不进行结构优化（ISIF=3），那么计算结果的趋势符合文献报道，跟用wine2k的趋势也一样。

引用回帖:

AFM1
  free  energy TOTEN  =    -61.279719 eV
AFM2
  free  energy TOTEN  =    -61.255735 eV
AFM3
  free  energy TOTEN  =    -61.189768 eV
AFM4
  free  energy TOTEN  =    -60.938984 eV
AFM5
  free  energy TOTEN  =    -60.879493 eV
AFM6
  free  energy TOTEN  =    -61.222014 eV
AFM7
  free  energy TOTEN  =    -61.169375 eV
FM
  free  energy TOTEN  =    -60.824646 eV
NM
  free  energy TOTEN  =    -61.00932 eV
End of all

如果对实验值进行优化，然后使用优化后的结构进行计算，不仅趋势不一样，而且基态也不是AFM1了：

引用回帖:

AFM1
  free  energy TOTEN  =    -61.301294 eV
AFM2
  free  energy TOTEN  =    -61.301168 eV
AFM3
  free  energy TOTEN  =    -61.222014 eV
AFM4
  free  energy TOTEN  =    -61.3327854 eV
AFM5
  free  energy TOTEN  =    -61.334349 eV
AFM6
  free  energy TOTEN  =    -61.222427 eV
AFM7
  free  energy TOTEN  =    -61.222014 eV
FM
  free  energy TOTEN  =    -61.332874 eV
NM
  free  energy TOTEN  =    -61.32873 eV
End of all

这是我在结构优化以及总能计算中用到的对FM的INCAR文件，其他的类似

引用回帖:

#######结构优化的INCAR#############
System = CaFe2As2 fm:cell
PREC = Accurate
ISPIN = 2
ISMEAR = 1
ISTART = 0
ICHARG = 2
IBRION = 2
SIGMA = 0.18
EDIFF = 1E-5
EDIFFG = -1E-4
GGA = PE
NSW = 100
ENCUT = 400
ISIF = 3 #Full relaxtion
POTIM = 0.2
ISYM = 0

LORBIT = 11
LREAL = .FALSE.
NPAR = 1
LPLANE = .TRUE.
LSCALU = .FALSE.
NSIM = 4
##########静态计算的INCAR##############
System = CaFe2As2 FM:dos
PREC = Accurate
ISPIN = 2
ISMEAR = -5
ISTART = 0
ICHARG = 2
SIGMA = 0.18
EDIFF = 1E-5
EDIFFG = -1E-4
GGA = PE
ENCUT = 400
POTIM = 0.2
ISYM = 0

LORBIT = 11
LREAL= .FALSE.
NPAR = 1
LPLANE = .TRUE.
NSIM = 4
###########非自洽计算的INCAR###########
System = CaFe2As2 fm:dos
PREC = Accurate
ISPIN = 2
ISMEAR = -5
ISTART = 1
ICHARG = 11
SIGMA = 0.18
EDIFF = 1E-5
EDIFFG = -1E-4
GGA = PE
ENCUT = 400
POTIM = 0.2
ISYM = 0

LORBIT = 11
LREAL= .FALSE.
NPAR = 1
LPLANE = .TRUE.
NSIM = 4

是结构优化的INCAR哪里不对？

[ Last edited by Prettyswan on 2011-3-24 at 10:12 ]

该体系存在collapse phase transition，导致（使用赝势的）理论计算跟实验值不符。

[ Last edited by Prettyswan on 2011-4-19 at 10:36 ]

回复此楼