Input Instructions for AVS Module Crystal: This module outputs a geometry object that contains a crystal structure view consisting of polyhedra, spheres, bonds, and the unit-cell boundary. The limits of view and it's origin are controlled by slider widgets. The orientation of the viewed object and colors, etc. are controlled by the geometry viewer. The description of the crystallography, which includes unit-cell parameters, space group and atomic coordinates, are input through a file that is selected by a file browser. Each line of this file is preceeded by a character sequence that describes the type of information, as follows: titl General description of the Structure cell unit-cell lengths and angles. spgp Space Group name consisting of the Bravais lattice symbol followed by a space, the elements parallel to the first axis followed by a space, etc. Examples are I 41/a m d, P 21/n, I a 3 d, P b n m, etc. The generators will always select the origin choice with a center of symmetry at the origin. Furthermore, all monoclinic cells will have the unique axis parallel to the b axis. sphere 'name' 'radius', where 'name' is a one- or two-character symbol of the atom type, and 'radius' is the radius of the sphere in Angstrom. There is a slider widget to permit a multiplier to be applied to all radii. bond 'name1' 'name2' 'radius' 'min length' max length', where 'name1' and 'name2' indicate the types of atoms to be connected by a bond, 'radius' is the radius of the resulting cylinder, and the minimum and maximum lengths are given in Angstrom. polysz 'name' 'length' defines a polyhedron, where 'name' is the name of an atom at the center of a polyhedron and 'length' is the maximum length of distances to atoms that are to be considered as the vertices of the polyhedron. No atoms that are mentioned in 'sphere' or 'polysz' commands will be considered as the vertices of a polyhedron. atom 'name' 'number' 'x' 'y' 'z' defines the atoms. The 1- or 2-character name will be used on the commands that describe the objects to be created, the number is to keep track of the atom, and 'x' 'y' 'z' are the fractional coordinates in the unit cell. end The last line of a file. Sample input file - In the sliders, set the origin at 0,0,0: title Buckyball cell 14.16 14.16 14.16 spgp F m 3 sphere c 0.4 bond c c 0.1 1.2 1.5 atom c 1 0.04908 0.00000 0.24510 atom c 2 0.10028 0.08284 0.21346 atom c 3 0.18313 0.05120 0.16226 end