lattice style scale keyword values ...-
The lattice style must be consistent with the dimension of the simulation - see the dimension command. Styles sc -or bcc or fcc or diamond are for 3d problems. Styles sq or -sq2 or hex are for 2d problems. Style custom can be used for -either 2d or 3d problems. +or bcc or fcc or hcp or diamond are for 3d problems. Styles +sq or sq2 or hex are for 2d problems. Style custom can be +used for either 2d or 3d problems.
A lattice consists of a unit cell, a set of basis atoms within that cell, and a set of transformation parameters (scale, origin, orient) @@ -89,22 +89,24 @@
Lattices of style sc, fcc, bcc, and diamond are 3d lattices that define a cubic unit cell with edge length = 1.0. This means a1 = -1.0 0.0 0.0, a2 = 0.0 1.0 0.0, and a3 = 0.0 0.0 1.0. The placement of -the basis atoms within the unit cell are described in any solid-state -physics text. A sc lattice has 1 basis atom at the -lower-left-bottom corner of the cube. A bcc lattice has 2 basis -atoms, one at the corner and one at the center of the cube. A fcc -lattice has 4 basis atoms, one at the corner and 3 at the cube face -centers. A diamond lattice has 8 basis atoms. +1 0 0, a2 = 0 1 0, and a3 = 0 0 1. Style hcp has a1 = 1 0 0, a2 = 0 +sqrt(3) 0, and a3 = 0 0 sqrt(8/3). The placement of the basis atoms +within the unit cell are described in any solid-state physics text. A +sc lattice has 1 basis atom at the lower-left-bottom corner of the +cube. A bcc lattice has 2 basis atoms, one at the corner and one at +the center of the cube. A fcc lattice has 4 basis atoms, one at the +corner and 3 at the cube face centers. A hcp lattice has 4 basis +atoms, two in the z = 0 plane and 2 in the z = 0.5 plane. A diamond +lattice has 8 basis atoms.
Lattices of style sq and sq2 are 2d lattices that define a square -unit cell with edge length = 1.0. This means a1 = 1.0 0.0 0.0 and a2 -= 0.0 1.0 0.0. A sq lattice has 1 basis atom at the lower-left -corner of the square. A sq2 lattice has 2 basis atoms, one at the -corner and one at the center of the square. A hex style is also a -2d lattice, but the unit cell is rectangular, with a1 = 1.0 0.0 0.0 -and a2 = 0.0 sqrt(3.0) 0.0. It has 2 basis atoms, one at the corner -and one at the center of the rectangle. +unit cell with edge length = 1.0. This means a1 = 1 0 0 and a2 = 0 1 +0. A sq lattice has 1 basis atom at the lower-left corner of the +square. A sq2 lattice has 2 basis atoms, one at the corner and one +at the center of the square. A hex style is also a 2d lattice, but +the unit cell is rectangular, with a1 = 1 0 0 and a2 = 0 sqrt(3) 0. +It has 2 basis atoms, one at the corner and one at the center of the +rectangle.
A lattice of style custom allows you to specify a1, a2, a3, and a list of basis atoms to put in the unit cell. By default, a1,a2,a3 are diff -Naur lammps-12Apr08/doc/lattice.txt lammps-13Apr08/doc/lattice.txt --- lammps-12Apr08/doc/lattice.txt 2008-02-29 18:13:20.000000000 -0700 +++ lammps-13Apr08/doc/lattice.txt 2008-04-11 14:09:19.000000000 -0600 @@ -12,7 +12,7 @@ lattice style scale keyword values ... :pre -style = {none} or {sc} or {bcc} or {fcc} or {diamond} or \ +style = {none} or {sc} or {bcc} or {fcc} or {hcp} or {diamond} or \ {sq} or {sq2} or {hex} or {custom} :ulb,l scale = scale factor between lattice and simulation box :l for style {none}: @@ -65,9 +65,9 @@ The lattice style must be consistent with the dimension of the simulation - see the "dimension"_dimension.html command. Styles {sc} -or {bcc} or {fcc} or {diamond} are for 3d problems. Styles {sq} or -{sq2} or {hex} are for 2d problems. Style {custom} can be used for -either 2d or 3d problems. +or {bcc} or {fcc} or {hcp} or {diamond} are for 3d problems. Styles +{sq} or {sq2} or {hex} are for 2d problems. Style {custom} can be +used for either 2d or 3d problems. A lattice consists of a unit cell, a set of basis atoms within that cell, and a set of transformation parameters (scale, origin, orient) @@ -81,22 +81,24 @@ Lattices of style {sc}, {fcc}, {bcc}, and {diamond} are 3d lattices that define a cubic unit cell with edge length = 1.0. This means a1 = -1.0 0.0 0.0, a2 = 0.0 1.0 0.0, and a3 = 0.0 0.0 1.0. The placement of -the basis atoms within the unit cell are described in any solid-state -physics text. A {sc} lattice has 1 basis atom at the -lower-left-bottom corner of the cube. A {bcc} lattice has 2 basis -atoms, one at the corner and one at the center of the cube. A {fcc} -lattice has 4 basis atoms, one at the corner and 3 at the cube face -centers. A {diamond} lattice has 8 basis atoms. +1 0 0, a2 = 0 1 0, and a3 = 0 0 1. Style {hcp} has a1 = 1 0 0, a2 = 0 +sqrt(3) 0, and a3 = 0 0 sqrt(8/3). The placement of the basis atoms +within the unit cell are described in any solid-state physics text. A +{sc} lattice has 1 basis atom at the lower-left-bottom corner of the +cube. A {bcc} lattice has 2 basis atoms, one at the corner and one at +the center of the cube. A {fcc} lattice has 4 basis atoms, one at the +corner and 3 at the cube face centers. A {hcp} lattice has 4 basis +atoms, two in the z = 0 plane and 2 in the z = 0.5 plane. A {diamond} +lattice has 8 basis atoms. Lattices of style {sq} and {sq2} are 2d lattices that define a square -unit cell with edge length = 1.0. This means a1 = 1.0 0.0 0.0 and a2 -= 0.0 1.0 0.0. A {sq} lattice has 1 basis atom at the lower-left -corner of the square. A {sq2} lattice has 2 basis atoms, one at the -corner and one at the center of the square. A {hex} style is also a -2d lattice, but the unit cell is rectangular, with a1 = 1.0 0.0 0.0 -and a2 = 0.0 sqrt(3.0) 0.0. It has 2 basis atoms, one at the corner -and one at the center of the rectangle. +unit cell with edge length = 1.0. This means a1 = 1 0 0 and a2 = 0 1 +0. A {sq} lattice has 1 basis atom at the lower-left corner of the +square. A {sq2} lattice has 2 basis atoms, one at the corner and one +at the center of the square. A {hex} style is also a 2d lattice, but +the unit cell is rectangular, with a1 = 1 0 0 and a2 = 0 sqrt(3) 0. +It has 2 basis atoms, one at the corner and one at the center of the +rectangle. A lattice of style {custom} allows you to specify a1, a2, a3, and a list of basis atoms to put in the unit cell. By default, a1,a2,a3 are diff -Naur lammps-12Apr08/doc/units.html lammps-13Apr08/doc/units.html --- lammps-12Apr08/doc/units.html 2008-04-10 14:53:47.000000000 -0600 +++ lammps-13Apr08/doc/units.html 2008-04-10 15:14:17.000000000 -0600 @@ -30,15 +30,20 @@ and dump files. Typically, this command is used at the very beginning of an input script.
-For real and metallic units, LAMMPS uses physical constants from +
For real and metal units, LAMMPS uses physical constants from www.physics.nist.gov. For the definition of Kcal in real units, LAMMPS uses the thermochemical calorie = 4.184 J.
-For style lj, all quantities are unitless. The formula relating the -reduced or unitless quantity (with an asterisk) to the same quantity -with units is also given: +
For style lj, all quantities are unitless. Without loss of +generality, LAMMPS sets the fundamental quantities mass, sigma, +epsilon, and the Boltzmann constant = 1. The masses, distances, +energies you specify are multiples of these fundamental values. The +formulas relating the reduced or unitless quantity (with an asterisk) +to the same quantity with units is also given. Thus you can use the +mass & sigma & epsilon values for a specific material and convert the +results from a unitless LJ simulation into physical quantities.
-For style real, these are the units:
-For style metal, these are the units:
-