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[求助]
关于POSCAR中晶矢的定义
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2楼2013-05-10 11:22:22
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8楼2013-05-10 15:09:49
liqizuiyang
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franch: 金币+2, 谢谢回帖交流,, 2013-05-13 21:32:56
感谢参与,应助指数 +1
franch: 金币+2, 谢谢回帖交流,, 2013-05-13 21:32:56
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楼主可以参考下PWscf的帮助文件,里面有14种布拉伐格子的原胞基矢的表达式。 ibrav structure celldm(2)-celldm(6) or: b,c,cosab,cosac,cosbc 0 free crystal axis provided in input: see card CELL_PARAMETERS 1 cubic P (sc) v1 = a(1,0,0), v2 = a(0,1,0), v3 = a(0,0,1) 2 cubic F (fcc) v1 = (a/2)(-1,0,1), v2 = (a/2)(0,1,1), v3 = (a/2)(-1,1,0) 3 cubic I (bcc) v1 = (a/2)(1,1,1), v2 = (a/2)(-1,1,1), v3 = (a/2)(-1,-1,1) 4 Hexagonal and Trigonal P celldm(3)=c/a v1 = a(1,0,0), v2 = a(-1/2,sqrt(3)/2,0), v3 = a(0,0,c/a) 5 Trigonal R, 3fold axis c celldm(4)=cos(alpha) The crystallographic vectors form a three-fold star around the z-axis, the primitive cell is a simple rhombohedron: v1 = a(tx,-ty,tz), v2 = a(0,2ty,tz), v3 = a(-tx,-ty,tz) where c=cos(alpha) is the cosine of the angle alpha between any pair of crystallographic vectors, tx, ty, tz are: tx=sqrt((1-c)/2), ty=sqrt((1-c)/6), tz=sqrt((1+2c)/3) -5 Trigonal R, 3fold axis <111> celldm(4)=cos(alpha) The crystallographic vectors form a three-fold star around <111>. Defining a' = a/sqrt(3) : v1 = a' (u,v,v), v2 = a' (v,u,v), v3 = a' (v,v,u) where u and v are defined as u = tz - 2*sqrt(2)*ty, v = tz + sqrt(2)*ty and tx, ty, tz as for case ibrav=5 6 Tetragonal P (st) celldm(3)=c/a v1 = a(1,0,0), v2 = a(0,1,0), v3 = a(0,0,c/a) 7 Tetragonal I (bct) celldm(3)=c/a v1=(a/2)(1,-1,c/a), v2=(a/2)(1,1,c/a), v3=(a/2)(-1,-1,c/a) 8 Orthorhombic P celldm(2)=b/a celldm(3)=c/a v1 = (a,0,0), v2 = (0,b,0), v3 = (0,0,c) 9 Orthorhombic base-centered(bco) celldm(2)=b/a celldm(3)=c/a v1 = (a/2, b/2,0), v2 = (-a/2,b/2,0), v3 = (0,0,c) -9 as 9, alternate description v1 = (a/2,-b/2,0), v2 = (a/2,-b/2,0), v3 = (0,0,c) 10 Orthorhombic face-centered celldm(2)=b/a celldm(3)=c/a v1 = (a/2,0,c/2), v2 = (a/2,b/2,0), v3 = (0,b/2,c/2) 11 Orthorhombic body-centered celldm(2)=b/a celldm(3)=c/a v1=(a/2,b/2,c/2), v2=(-a/2,b/2,c/2), v3=(-a/2,-b/2,c/2) 12 Monoclinic P, unique axis c celldm(2)=b/a celldm(3)=c/a, celldm(4)=cos(ab) v1=(a,0,0), v2=(b*cos(gamma),b*sin(gamma),0), v3 = (0,0,c) where gamma is the angle between axis a and b. -12 Monoclinic P, unique axis b celldm(2)=b/a celldm(3)=c/a, celldm(5)=cos(ac) v1 = (a,0,0), v2 = (0,b,0), v3 = (c*sin(beta),0,c*cos(beta)) where beta is the angle between axis a and c 13 Monoclinic base-centered celldm(2)=b/a celldm(3)=c/a, celldm(4)=cos(ab) v1 = ( a/2, 0, -c/2), v2 = (b*cos(gamma), b*sin(gamma), 0), v3 = ( a/2, 0, c/2), where gamma is the angle between axis a and b 14 Triclinic celldm(2)= b/a, celldm(3)= c/a, celldm(4)= cos(bc), celldm(5)= cos(ac), celldm(6)= cos(ab) v1 = (a, 0, 0), v2 = (b*cos(gamma), b*sin(gamma), 0) v3 = (c*cos(beta), c*(cos(alpha)-cos(beta)cos(gamma))/sin(gamma), c*sqrt( 1 + 2*cos(alpha)cos(beta)cos(gamma) - cos(alpha)^2-cos(beta)^2-cos(gamma)^2 )/sin(gamma) ) where alpha is the angle between axis b and c beta is the angle between axis a and c gamma is the angle between axis a and b |
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