VASP 的光学性质计算及 vaspkit 的安装与使用

---

使用的软件：VASP, Origin, SshClient, vaspkit.0.51

---

一 光学性质计算

在完成结构优化和静态计算后，拷贝 scf 文件夹为 optic

cp -rf scf optic

编辑 optic 文件夹下 INCAR

INCAR

SYSTEM=x
ISTART=0
ENCUT=350
EDIFF=1E-5
IBRION=-1 # change
POTIM=0.25
NSW=0 # change
EDIFFG=-1E-2
ISMEAR=0
SIGMA=0.05
PREC=ACCURATE
ISIF=2
NPAR=1 # change 4 to 1
#LWAVE=FALSE
#LCHARG=FALSE
LREAL=Auto
#IALGO=48
ISYM=0
NBANDS=x # add
LOPTICS=.TRUE. # add

• 注：NBANDS=x x 为 OUTCAT 中 NBANDS*2, 可使用 grep 命令查询

grep NBANDS OUTCAR

提交作业，计算完成后，可查看 OUTCAR 文件，有计算得出介电常数 (Dielectric constant) 的实部和虚部。

  frequency dependent IMAGINARY DIELECTRIC FUNCTION (independent particle, no local field effects)
     E(ev)      X         Y         Z        XY        YZ        ZX

  frequency dependent      REAL DIELECTRIC FUNCTION (independent particle, no local field effects)
     E(ev)      X         Y         Z        XY        YZ        ZX

使用 vaspkit 程序对计算结果进行处理。

二 vaspkit 的安装与使用

安装 Installation

使用 SshClient 将已下载的 vaspkit 导入 linux 服务器，安装步骤：

tar -zvxf vaspkit.*.tar.gz
cd vaspkit.*/src
modify the Makefile file based on your machine environment;
make

• Note that the formats of POSCAR, CONCAR and CHGCAR files in VASP.5.x are slightly different from those in VASP.4.x. Please set the vasp5=.false. in the src/module.f90 file if you use VASP.4.x

设置环境变量

vi ~/.bashrc
alias opt="~/software/vaspkit.0.51/examples/optic/optics.sh"
alias kit="~/software/vaspkit.0.51/src/vaspkit"
source ~/.bashrc

• You need to preparethe REAL.IN and IMAG.IN files which include the real and imaginary parts of frequencydependent complex dielectric function. There is a bash script optics.sh as a reference in the vaspkit.*/examples/optic/ could help you to prepare the real.in and imag.in files.

光学数据处理

输入命令opt产生 REAL.IN 和 IMAG.IN 文件，依次输入命令kit和51，屏幕显示如下

 +---------------------------------------------------+
 |       VASPKIT Version: 0.51 (10 Oct. 2016)        |
 |    A Postprocessing Toolkit For VASP.5.x Code     |
 |    Developed By Vei WANG ([email protected])     |
 +---------------------------------------------------+

 =============== Structural Options ==================
 2)  Elastic Constant Calculator
 3)  Structure Converting  4) Supercell Building
 5)  EOS Fitting           6) Symmetry Toolkit
 7)  K-Mesh Generating
 8)  Band-Structure Path Generating (experimental)

 =============== Electronic Options ==================
 11) Total DOS            12) Projected DOS
 13) l-m Decomposed DOS
 21) Band-Structure       22) Projected Band-Structure
 23) 3D Band-Structure for Two-Dimensional Materials
 24) One Specific Band-Structure

 ======== Charge Density & Potential Options =========
 31) CHG Density          32) Spin Density
 33) Spin-Up & -Down Density
 34) CHG Difference       35) Spin Density Difference
 41) Planar-Average CHG   42) Planar-Average POT

 =============== Optical Options =====================
 51) Linear Optics

 ================ Misc Utilities =====================
 91) Semiconductor Calculator
 92) VASP2BoltzTraP

 0)  Quit
 ------------>>
51
 +---------------------------------------------------+
 |    Please prepared IMAG.in and REAL.in files      |
 |               before runing optics                |
 |...................................................|
 |  Calculate absorb,refractive,energylossspectrum,  |
 |        extinctionr and reflectivity (in eV).      |
 +---------------------------------------------------+

 -->> (1) Reading IMAG.in and REAL.in Files...
 -->> (2) Written Optical Files Succesfully!
 +---------------------------------------------------+
 |                   * DISCLAIMER *                  |
 |    CANNOT Guarantee Reliability of VASPKIT Code   |
 |  CHECK Your Results for Consistency If Necessary  |
 |               (^.^) GOOD LUCK (^.^)               |
 +---------------------------------------------------+

输出文件 ABSORB.dat，REFRACTIVE.dat，REFLECTIVITY.dat，EXTINCTION.dat 和 ENERGYLOSSSPECTRUM.dat，依次为 absorption coefficient, refractive coefficient, reflectivity coefficient, extinction coefficient and energy-loss function。导出使用 Origin 作图即可。

---

附：相关光学性质计算公式