最终SIGMA = 0.05, ALGO = A ,收敛。供参考。谢谢各位前辈!
问题:DFT+U,SCF不收敛,我不知道怎么办了,卡半个月了。拜托各位前辈帮我看看。文中按顺序贴出了我的INCAR,尝试过的方法以及结构信息。(再补充,不加U时,收敛)
1. INCAR信息如下
# control
SYSTEM=ceo2-OPT
#SYMPREC=1E-10
LCHARG=.FALSE.
LWAVE=.FALSE.
NPAR=4
LREAL=A
LMAXMIN=6
#SCF
ALGO=F
EDIFF=1E-5
ISMEAR=0
SIGMA=0.1
PREC=NORMAL
NELM=150
NELMIN=6
ENCUT=400
#LVDW=.T.
LDAU=.True.
LDAUL=-1 3 -1 -1 -1
LDAUU=0 5 0 0 0
#OPT
EDIFFG=-0.05
NSW=200
IBRION=2 # 0: MD, 1: Newton, 2: CG, 7:frequency
ISIF=2 # 3 for bulk, 2 for surface and others
#IDIPOL=3 # 1: x, 2:y, 3, z, 4: all
ADDGRID=.TRUE. # use when IBRION=1
AMIN = 0.01
AMIX = 0.20
BMIX = 0.00001
AMIX_MAG = 0.80
BMIX_MAG = 0.00001
2. 按照前辈的方法依次尝试
http://bbs.keinsci.com/thread-11126-1-2.html
(1)调整了很多构型,DFT能优化成功,DFT+U(u=5失败)。排除构型不合理原因。
(2)添加LMAXMIN=6,仍然不收敛
(3)没有读取波函数
(5)SIGMA=0.5是粗收敛,提高SIGMA=0.1后不收敛 AMIX = 0.2
BMIX = 0.0001 #almost zero, but 0 will crash some versions
BMIX = 0.0001 #almost zero, but 0 will crash some versions BMIX MAG = 0.0001 #almost zero, but 0 will crash some versions (7) CeO2是半导体,所以设置ISMEAR=0 (8) 检查体系是不是特殊的磁性排列,即MAGMOM设置是否合理。(关于这点,我的ISPIN=1,还需要考虑吗?如何检查体系的磁性排列?) (9) 提高积分精度,PREC=Accurate 。(尝试不收敛) (10) 提高格点精度,ADDGRID = .TRUE. 。(尝试不收敛) (11) 先用1 1 1 K点计算收敛,再读取CHGCAR,用高K点计算。(现在是K=331,尝试G=111,不收敛) (12) 尝试不同的ALGO 比如:ALGO=Conjugate。(测试中) (13) 如果在结构优化或者MD过程中,某一步突然不收敛,使用MAXMIX = 50(不相干,未尝试) (14) 尝试用更小的ENCUT或者更大的ENCUT的预收敛。(原先是400,调整过450,不收敛) (15) 换更小的赝势或者更soft的赝势。(赝势中Ce有Ce Ce_3 Ce_GW Ce_h,四个文件,目前选用的是Ce <PAW_PBE Ce 23Dec2003> 。我不知道如何区分软硬,待查询
(16) 最后给出一个VASP官方教程里解决的不收敛的方法: 1.用ALGO=N (是否收敛N to 2,Y to 6) 2. ICHARG=12 (no charge update,非自洽计算,N to5, Y to 3) 3. ICHARG=2 AMIX=0.1 ; BMIX=0.01(N to 4, Y to 6) 4. increase BMIXBMIX=3.0 ; AMIN=0.01(N to 5, Y to 6) (这里关于括号中的注释我不理解意思)
3. 结构信息
FM3M 110面 supercell:3*3 3层固定底部一层
POSCAR
111\(4)
1.00000000000000
10.6602001190000006 0.0000000000000000 0.0000000000000000
0.0000000000000000 11.3069000244000009 0.0000000000000000
0.0000000000000000 0.0000000000000000 27.5379009247000006
O Ce Pt H C
36 17 1 8 3
Selective dynamics
Direct
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