vasp算微波介电常数

**首先计算动力学
会得到XDATCAR
使用deal.py做一个Data文件（改原子数）**
```python
ff = open('data','w')
ff.write('\n')
for _ in range(100):    #POSCAR中元素1的原子个数
    ff.write('1\n')
#ff.close()
#ff = open('data','w')
#ff.write('\n')
for _ in range(100):    #POSCAR中元素2的原子个数
    ff.write('2\n')
ff.close()

```
**然后在服务器里面用这个脚本correlation_vasp.sh（改步数）**
```bash
#bin/bash
#24 December, 2021;Data Extraction
#To use it: bash r_dat
for i in {1..10000};  #aimd step
do
cp data data-$i
done
for i in {1..10000};
do
cat data-$i >> data1   #Generate atomic numbers
done
rm data-*

cat XDATCAR | sed '1,7d' > data2  
paste data1 data2 > data.dat  #整合数据

```
**得到data.dat文件后拿出来放进matlab里面处理数据correlation_vasp.m（改保存地址和原子数）**
```
clear all
close all

%Enter Parameters
number=256;   %number of atoms
dt=1;          %dump gap
numbera=10000;   %calculate the C(t) number; The number of data points to draw the graph; Usually we take 200
q=-1;         %electric charge
t=0;           %Calculate the C(t) of the autocorrelation function from t=0 to t=t (Time_max=timestep*Nfreq)
x_columns=2;   %Number of vx columns in dump file
y_columns=3;   %Number of vy columns in dump file
z_columns=4;   %Number of vy columns in dump file
fid = fopen('data.dat');   %open dump file

data = textscan(fid, '%s',  'Delimiter', '\n');
count=[];
data=data{1,1};
for i=1:length(data)
    if strfind(data{i,1},'Direct configuration=');
        count=[count,i];
    end
end
k=1;
for j=1:length(count)

for i=(count(j)+1):(count(j)+number)
          aaa(k)=data(i,1);
        k=k+1;
    end
end
data=str2num(char(aaa));
for j=1:length(count)
    sumx=0;sumy=0;sumz=0;
    for i=1:number
        x=(j-1)*number+i;
    if  data(x,1)==1                                       %index of atom 1
        sumx=sumx+data(x,x_columns)*q;
        sumy=sumy+data(x,y_columns)*q;
        sumz=sumz+data(x,z_columns)*q;
    elseif data(x,1)==2                                   %index of atom 2
        sumx=sumx+data(x,x_columns)*(-q);
        sumy=sumy+data(x,y_columns)*(-q);
        sumz=sumz+data(x,z_columns)*(-q);
    end

end
    vx(j)=sumx;
    vy(j)=sumy;
    vz(j)=sumz;
end

for j=1:numbera

Cx=0; Cy=0;Cz=0;Call=0;
for i=1:(length(vx)-t)
    Cx=vx(i)*vx(i+t)+Cx;
    Cy=vy(i)*vy(i+t)+Cy;
    Cz=vz(i)*vz(i+t)+Cz;
    Call=(vx(i)+vy(i)+vz(i))*(vx(i+t)+vy(i+t)+vz(i+t))+Call;
end
    cx(j)=Cx/(length(vx)-t);
    cy(j)=Cy/(length(vy)-t);
    cz(j)=Cz/(length(vz)-t);
    call(j)=Call/(length(vx)-t);
    
    t=t+1;
    
 end
    c= [cx;cy;cz;call]';       %the C(t) of the autocorrelation function
    m=[0:dt:dt*(numbera-1)]';   %add index
    C=[m c];                    %composite matrix
    save('C:\Users\82399\Desktop\output.txt','c','-ascii')

%%%%%Fourier transform and plot
    %%%%%%%reference https://zhidao.baidu.com/question/235280965.html%%
    ta=C(:,1);                  %time
    cvx=C(:,2);                %data cvx
    cvy=C(:,3);
    cvz=C(:,4);
    cvall=C(:,5);
    dt=ta(2)-ta(1);              %dt:Sampling time interval
    fs=1/dt;                   %The maximum value of the Fourier transform; It's reciprocal with time
    cax=abs(fft(cvx));         %Fourier transform
    cay=abs(fft(cvy));
    caz=abs(fft(cvz));
    caall=abs(fft(cvall));
    f=(0:length(ta)-1)*fs/length(ta);  
    ca=[cax cay caz caall];
    %%%plot figure
    figure();
    subplot(811);
    plot(ta,cvx);
    subplot(812);
    plot(f(1:numbera/2),cax(1:numbera/2));
    subplot(813);
    plot(ta,cvy);
    subplot(814);
    plot(f(1:numbera/2),cay(1:numbera/2));
    subplot(815);
    plot(ta,cvz);
    subplot(816);
    plot(f(1:numbera/2),caz(1:numbera/2));
    subplot(817);
    plot(ta,cvall);
    subplot(818);
    plot(f(1:numbera/2),caall(1:numbera/2));
    
    save('C:\Users\82399\Desktop\output2.txt','ca','-ascii') 
```
**matlab会直接生成图
x,y,z方向和总和的震荡图以及他们的傅里叶变换，共八个小图，跟下面示范图不一样**
![](/media/202303/2023-03-12_212506_2341180.3119739998147609.png)
**得到output1和output2,放进oringin作图
**
![](/media/202303/2023-03-12_212724_4714570.9497949280118622.png)

vasp算微波介电常数

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vasp算微波介电常数

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