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zjucy

金虫 (小有名气)

应助: 1 (幼儿园)
金币: 44.6
散金: 37
帖子: 110
在线: 142.8小时
虫号: 439041
注册: 2007-10-06
专业: 机构学与机器人

[求助] TiO2 晶胞参数优化问题

最近在这里卡了好久  还请各位前辈指点一下看看是哪里出了问题。
（用的原胞如图所示）

INCAR
TiO2-unit-cell
ENCUT=450
ISTART=0;ICHARG=2
ISMEAR=0;SIGMA=0.2
NSW=60;IBRION=2
ISIF=3
POTIM=0.2
EDIFF=1E-6;EDIFFG=-1E-3
PREC=Accurate
NPAR=4

KPOINTS

Automatic generation
0
Monhkorst-Pack
9 9 9
0.0 0.0 0.0

脚本
#!/bin/sh
rm WAVECAR
for i in  9.436 9.446 9.456 9.466 9.476 9.486 9.496 9.506 9.516 9.526 9.536
do
cat > POSCAR << !
SYSTEM=TiO2-unit
$i
0.3980602994 0.0000000000 0.0000000000
0.0000000000 0.3980602994 0.0000000000
0.0000000000 0.0000000000 1.0000000000
4 8
Direct
0.0000000000 0.0000000000 0.0000000000
0.5000000000 0.5000000000 0.5000000000
0.0000000000 0.5000000000 0.2500000000
0.5000000000 0.0000000000 0.7500000000
0.0000000000 0.0000000000 0.2080000000
0.5000000000 0.5000000000 0.7080000000
0.0000000000 0.5000000000 0.0420000000
0.5000000000 0.0000000000 0.5420000000
0.0000000000 0.0000000000 -0.2080000000
0.5000000000 0.5000000000 0.2920000000
0.0000000000 0.5000000000 0.4580000000
0.5000000000 0.0000000000 0.9580000000
!
echo "a=$i angstrom" ;  time mpiexec -np 16 vasp

E=`grep "TOTEN" OUTCAR | tail -1 | awk '{printf "%12.6f\n",$5}'`
V=`grep "volume" OUTCAR | tail -1 | awk '{printf "%12.4f\n",$5}'`
echo $E $V >> EtVo.dat
echo $i : $V $E >> SUMMARY
cp OUTCAR OUTCAR.$i
cp CONTCAR CONTCAR.$i
done
计算完成后得到的不是二次曲线而是锯齿状的。如图所示。不知道这个问题出在哪里。

还有就是用二步法优化的话出来的结果也不是二次曲线，而是斜率为负的直线。也请各位前辈帮忙看看问题出在哪里

INCAR.relax

TiO2-unit
ENCUT=450
ISTART=0;ICHARG=2
ISMEAR=0;SIGMA=0.02
NSW=60;IBRION=2
ISIF=4
POTIM=0.2
EDIFF=1E-5;EDIFFG=-1E-3
PREC=Accurate
NPAR=4

INCAR.static

TiO2-unit
ENCUT=450
ISTART=0;ICHARG=2
ISMEAR=-5
NPAR=4
PREC=Accurate

KPOINTS:

Automatic generation
0
Monhkorst-Pack
9 9 9
0.0 0.0 0.0

脚本

#!/bin/sh
rm WAVECAR
for i in 循环值
do
cat > POSCAR << !
SYSTEM=TiO2-unit
$i
0.3980602994 0.0000000000 0.0000000000
0.0000000000 0.3980602994 0.0000000000
0.0000000000 0.0000000000 1.0000000000
4 8
Direct
0.0000000000 0.0000000000 0.0000000000
0.5000000000 0.5000000000 0.5000000000
0.0000000000 0.5000000000 0.2500000000
0.5000000000 0.0000000000 0.7500000000
0.0000000000 0.0000000000 0.2080000000
0.5000000000 0.5000000000 0.7080000000
0.0000000000 0.5000000000 0.0420000000
0.5000000000 0.0000000000 0.5420000000
0.0000000000 0.0000000000 -0.208000000
0.5000000000 0.5000000000 0.2920000000
0.0000000000 0.5000000000 0.4580000000
0.5000000000 0.0000000000 0.9580000000
!
cp INCAR.relax INCAR
echo "relax a=$i angstrom" ;  time mpiexec -np 16 vasp >/dev/null
cp CONTCAR POSCAR
cp INCAR.static INCAR
echo "static a=$i angstrom" ;  time mpiexec -np 16 vasp >/dev/null

E=`grep "TOTEN" OUTCAR | tail -1 | awk '{printf "%12.6f\n",$5}'`
V=`grep "volume" OUTCAR | tail -1 | awk '{printf "%12.4f\n",$5}'`
echo $i : $V $E >> SUMMARY
cp OUTCAR OUTCAR.$i
done

optonce.JPG