#!/usr/bin/python

# -*- coding: UTF-8 -*-

#by ZhiQiang Zhao  email:ZhiqiangZhao55@163.com

#KPOINTS for 3D band structure:

#########################################################

import os

import numpy as np

import math

'''

b1 = 2 π ( a2 × a3) /ν

b2 = 2 π ( a3 × a1) /ν

b3 = 2 π ( a1 × a2) /ν

v=a1.a2×a3

'''

##########定义一个函数为了向量叉乘积####################

def Vector_fork(a,b):

a1=a[0];a2=a[1];a3=a[2];

b1=b[0];b2=b[1];b3=b[2];

c=[a2*b3-a3*b2,a3*b1-a1*b3,a1*b2-a2*b1] #c=a×b

return c

################计算原胞的体积、倒格矢b1,b2,b3###########

path1="./POSCAR"

f1=open(path1,'r')

a=list()

p=0

while(p<7):

p+=1

line=f1.readline()

arr=line.split()

if(p in np.arange(3,6,1)):

a.append(arr[0:3])

a1 = [ float(x) for x in a[0] ]

a2 = [ float(x) for x in a[1] ]

a3 = [ float(x) for x in a[2] ]

v0=Vector_fork(a2,a3) 

V=np.inner(np.array(v0),np.array(a1))  

b1=(2*math.pi/V)*np.array(Vector_fork(a2,a3))

b2=(2*math.pi/V)*np.array(Vector_fork(a3,a1))

b3=(2*math.pi/V)*np.array(Vector_fork(a1,a2))

f1.close

################撒点#####################################

a=input("Please input the precision of the Kpoints：")#撒点步进量；

xmin=-0.5;xmax=0.5;

ymin=0.3;ymax=1.06;

z=0

h1='k-points along high symmetry lines'

knumber=((xmax-xmin)/a+1)*((ymax-ymin)/a+1)

h2='Reciprocal lattice'

f2=open('./KPOINTS','w')

f2.write(str(h1)+'\n'+' '+str(int(knumber))+'\n'+str(h2)+'\n')

for x in np.arange(xmin,(xmax+a), a):

for y in np.arange(ymin,(ymax+a), a):

num=[x,y,z]

A=np.mat(num)

B=np.mat([b1,b2,b3])

B1=np.linalg.inv(B)#求B的逆矩阵B1

#倒格子基矢矩阵

C=A*B1

l=float(C[:,0]);m=float(C[:,1]);n=float(C[:,2])

f2.writelines(' {0:.5f} {1:.5f} {2:.5f}   {3:.0f}'.format(l,m,n,1)+'\n')

f2.close

K.py