diff --git a/doc-def/INPUT_PW.def b/doc-def/INPUT_PW.def index ac7124968..b5535f1cf 100644 --- a/doc-def/INPUT_PW.def +++ b/doc-def/INPUT_PW.def @@ -354,116 +354,94 @@ input_description -distribution {Quantum Espresso} -package PWscf -program pw.x var ibrav -type INTEGER { status { REQUIRED } info { - Bravais-lattice index: - - ibrav structure celldm(2)-celldm(6) - - 0 "free", see above not used - 1 cubic P (sc) not used - 2 cubic F (fcc) not used - 3 cubic I (bcc) not used - 4 Hexagonal and Trigonal P celldm(3)=c/a - 5 Trigonal R, 3fold axis c celldm(4)=cos(alpha) - -5 Trigonal R, 3fold axis <111> celldm(4)=cos(alpha) - 6 Tetragonal P (st) celldm(3)=c/a - 7 Tetragonal I (bct) celldm(3)=c/a - 8 Orthorhombic P celldm(2)=b/a,celldm(3)=c/a - 9 Orthorhombic base-centered(bco) celldm(2)=b/a,celldm(3)=c/a - 10 Orthorhombic face-centered celldm(2)=b/a,celldm(3)=c/a - 11 Orthorhombic body-centered celldm(2)=b/a,celldm(3)=c/a - 12 Monoclinic P, unique axis c celldm(2)=b/a,celldm(3)=c/a, - celldm(4)=cos(ab) - -12 Monoclinic P, unique axis b celldm(2)=b/a,celldm(3)=c/a, - celldm(5)=cos(ac) - 13 Monoclinic base-centered celldm(2)=b/a,celldm(3)=c/a, - celldm(4)=cos(ab) - 14 Triclinic celldm(2)= b/a, - celldm(3)= c/a, - celldm(4)= cos(bc), - celldm(5)= cos(ac), - celldm(6)= cos(ab) - - For P lattices: the special (or unique) axis (c) is the z-axis, one basal-plane - vector (a) is along x, the other basal-plane vector (b) is at angle - gamma for monoclinic, at 120 degrees for trigonal and hexagonal - lattices, at 90 degrees for cubic, tetragonal, orthorhombic lattices - Alternate choice (more commonly used in crystallography) for monoclinic: - axis b is unique (orthogonal to a); axis c forms angle beta with axis a. - - sc simple cubic - ==================== - v1 = a(1,0,0), v2 = a(0,1,0), v3 = a(0,0,1) - - fcc face centered cubic - ==================== - v1 = (a/2)(-1,0,1), v2 = (a/2)(0,1,1), v3 = (a/2)(-1,1,0). - - bcc body entered cubic - ==================== - v1 = (a/2)(1,1,1), v2 = (a/2)(-1,1,1), v3 = (a/2)(-1,-1,1). - - simple hexagonal and trigonal(p) - ==================== - v1 = a(1,0,0), v2 = a(-1/2,sqrt(3)/2,0), v3 = a(0,0,c/a). - - trigonal(r) - =================== - ibrav=5: The z-axis is chosen as the 3-fold axis, the crystallographic - vectors form a three-fold star around the z-axis, the primitive cell - is a simple rhombohedron. The crystallographic vectors are: - 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, tc, ty, tz are defined as + Bravais-lattice index. In all cases except ibrav=0, + either [celldm(1)-celldm(6)] or [a,b,c,cosab,cosac,cosbc] + must be specified: see their description. For ibrav=0 + you may specify the lattice parameter celldm(1) or a. + + 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) - ibrav=-5, alternate description: the crystallographic vectors are - v1 = a/sqrt(3) (u,v,v), v2 = a/sqrt(3) (v,u,v), v3 = a/sqrt(3) (v,v,u) - and form a three-fold star around <111>. u and v are defined as + -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 - simple tetragonal (p) - ==================== - v1 = a(1,0,0), v2 = a(0,1,0), v3 = a(0,0,c/a) - - body centered tetragonal (i) - ================================ - v1 = (a/2)(1,-1,c/a), v2 = (a/2)(1,1,c/a), v3 = (a/2)(-1,-1,c/a). - - simple orthorhombic (p) - ============================= - v1 = (a,0,0), v2 = (0,b,0), v3 = (0,0,c) - - bco base centered orthorhombic - ============================= - v1 = (a/2,b/2,0), v2 = (-a/2,b/2,0), v3 = (0,0,c) - - face centered orthorhombic - ============================= - v1 = (a/2,0,c/2), v2 = (a/2,b/2,0), v3 = (0,b/2,c/2) - - body centered orthorhombic - ============================= - v1 = (a/2,b/2,c/2), v2 = (-a/2,b/2,c/2), v3 = (-a/2,-b/2,c/2) - - monoclinic (p) - ============================= - v1 = (a,0,0), v2= (b*cos(gamma), b*sin(gamma), 0), v3 = (0,0,c) - (unique axis c) where gamma is the angle between axis a and b. - Alternate choice (ibrav=-12) uses b as unique axis: - v1 = (a,0,0), v2 = (0,b,0), v3 = (a*sin(beta),0,c*cos(beta)) - where beta is the angle between axis a and c - - base centered monoclinic - ============================= - 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 - - triclinic - ============================= - 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), + 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 = (a*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