我用的VASP5.2 下的LEPSILON-tag算的压电系数和BEC等东西,之前发过类似的贴,不过这次想一起贴上来在好好求助一下:
我的INCAR
SYSTEM=PLPK
ENCUT=400
PREC=Normal
ISMEAR=0
SIGMA=0.05
EDIFF=1E-3
ISTART=0
ICHARG=2
IBRION=8
POTIM=0.1
LEPSILON=.TRUE.
LDAU=.TRUE.
LDAUTYPE=2
LDAUL=-1 -1 3 -1 -1 -1 -1 -1 -1
LDAUU=0 0 6 0 0 0 0 0 0
LDAUJ=0 0 0 0 0 0 0 0 0
LDAUPRINT=2
算的是一个20个原子的四方相结构,含极性不连续的。主要算它的极化强度和压电特性在应变条件下的变化,现在只是OUTCAR中的结果还差那么点儿分析,想多请教下算过相关内容的前辈和同行,希望不吝赐教。
比如0应变的结构,我从OUTCAR中找到的有用内容如下:(目前提取出来了弹性模量,BEC和压电张量矩阵,还有个介电张量)
MACROSCOPIC STATIC DIELECTRIC TENSOR (including local field effects in DFT)
---------------------------------------------
7.562 0.000 0.000
0.000 7.562 0.000
0.000 0.000 6.072
---------------------------------------------
PIEZOELECTRIC TENSORfor field in x, y, z (eAngst)
XX YY ZZ XY YZ ZX
--------------------------------------------------------------------------------
x -0.57655 0.53337 1.41549 0.00000 0.00000 -2.48765
y 0.74595 -0.80028 0.02920 0.00000 -2.29471 0.00000
z -2.13003 -2.13003 -1.71919 0.00000 0.00000 0.00000
PIEZOELECTRIC TENSORfor field in x, y, z (C/m^2)
XX YY ZZ XY YZ ZX
--------------------------------------------------------------------------------
x 0.00000 0.00000 0.00000 0.00000 0.00000 -0.16001
y 0.00000 0.00000 0.00000 0.00000 -0.16005 0.00000
z -0.14256 -0.14256 -0.11506 0.00000 0.00000 0.00000
BORN EFFECTIVE CHARGES (in e, cummulative output)
-------------------------------------------------
ion 1
1 4.16337 0.00000 -0.35555
2 0.00000 4.25218 -0.00273
3 0.00000 0.00000 3.08453
ion 2
1 5.65192 0.00000 -1.45143
2 0.00000 5.62322 0.02908
3 0.00000 0.00000 6.09140
ion 3
1 4.59437 0.00000 -0.77293
2 0.00000 4.57861 0.02654
3 0.00000 0.00000 4.69899
ion 4
1 2.97250 0.00000 -0.46660
2 0.00000 2.96029 0.01771
3 0.00000 0.00000 4.07500
ion 5
1 4.17827 0.00000 -0.05032
2 0.00000 4.15128 0.00691
3 0.00000 0.00000 3.68609
ion 6
1 6.14756 0.00000 0.98037
2 0.00000 6.12975 -0.01380
3 0.00000 0.00000 4.99445
ion 7
1 1.18633 0.00000 0.29818
2 0.00000 1.18496 -0.00823
3 0.00000 0.00000 1.34329
ion 8
1 8.15684 0.00000 0.91563
2 0.00000 7.88065 -0.02060
3 0.00000 0.00000 6.62523
ion 9
1 -2.67478 0.00000 0.42944
2 0.00000 -4.21338 0.03375
3 0.00000 0.00000 -2.01709
ion 10
1 -4.10024 0.00000 0.31148
2 0.00000 -2.70871 -0.04404
3 0.00000 0.00000 -2.01709
ion 11
1 -3.29422 0.00000 0.52821
2 0.00000 -3.19993 -0.00621
3 0.00000 0.00000 -4.46866
ion 12
1 -3.03210 0.00000 0.35551
2 0.00000 -2.55061 0.00564
3 0.00000 0.00000 -3.0
ion 13
1 -2.56321 0.00000 0.32517
2 0.00000 -2.93166 -0.02865
3 0.00000 0.00000 -3.0
ion 14
1 -2.59899 0.00000 0.66267
2 0.00000 -2.64079 -0.01770
3 0.00000 0.00000 -3.98642
ion 15
1 -2.45927 0.00000 -0.27148
2 0.00000 -4.36881 0.03943
3 0.00000 0.00000 -1.74718
ion 16
1 -4.39566 0.00000 -0.19074
2 0.00000 -2.44264 -0.03256
3 0.00000 0.00000 -1.74718
ion 17
1 -3.00654 0.00000 -0.27400
2 0.00000 -3.01064 -0.00666
3 0.00000 0.00000 -3.64142
ion 18
1 -2.6 0.00000 0.01679
2 0.00000 -5.89128 0.02448
3 0.00000 0.00000 -1.75444
ion 19
1 -6.05680 0.00000 -0.01867
2 0.00000 -2.16964 -0.03114
3 0.00000 0.00000 -1.75444
ion 20
1 -1.57589 0.00000 -0.92688
2 0.00000 -1.56198 0.02343
3 0.00000 0.00000 -4.92454
另外还有个离子贡献的介电张量:
MACROSCOPIC STATIC DIELECTRIC TENSOR IONIC CONTRIBUTION
---------------------------------------------
0.155 -0.004 -0.114
-0.004 0.000 0.001
-0.114 0.001 7.979
---------------------------------------------
那么问题来了:
1、首先是两个压电张量,为什么除了单位不一样,它们输出的格式也不一样,后者好多项是0,请问那是eij 的矩阵吗?可不可以换算成dij 的矩阵?
2、离子的介电张量贡献有用吗?或者说这部分贡献分析什么东西有用?
目前就这俩问题,请大神们帮看看吧!!!