1.2.2. FEATURES OF BALSAC/CLUSTER

next, previous Section / Table of Contents / Index BALSAC/CLUSTER allows you to construct, visualize, and analyze atom clusters of any complexity. Examples are molecules, clusters, finite sections of crystal lattices, of surfaces, of adsorbates on surfaces, or of interfaces. In the following we will always call these systems "clusters". Starting from a set of atom definitions (coordinates, nuclear charges, provided interactively or by transfer from BALSAC/LATTICE or using external input files) the cluster can be visualized or listed numerically by appropriate atom coordinates. Further, BALSAC/CLUSTER allows you to analyze local symmetries and geometries in a given cluster. It is interactive and uses the same menu strategies as BALSAC/LATTICE with many options being identical or similar. The user may start from scratch building a cluster or he/she can start with structures generated by previous BALSAC runs. Atom clusters can be modified by adding or deleting (hiding) atoms. Further, local groups of atoms may be selected and manipulated interactively. Possible transformations include rotation, translation, copying, or hiding/deleting. BALSAC/CLUSTER includes the same graphical visualization options as BALSAC/LATTICE. Here clusters are displayed as 3-dimensional arrays of atoms starting with the atoms farthest away from the viewer and allowing for various graphical manipulations such as size reduction / enlargement, rotation about the viewing direction, or changes in perspective. Atom coordinates, distances, and angles in a cluster may by determined directly from the screen output using a graphical pointer (keyboard or mouse). The pointer can also be used to select atoms and define subgroups interactively. In addition to graphical display all cluster atoms can be listed by their numerical coordinates and saved for separate graphical/numerical applications on external files. These files are ASCII-type and may be modified with text editors and used as input for subsequent runs of BALSAC/CLUSTER or other programs. The atoms of a cluster can be transferred to BALSAC/LATTICE to form the elementary cell of a 3-dimensional lattice allowing the user to build very complex molecular crystals. BALSAC/CLUSTER allows file output of structure and graphics data in various ASCII formats for subsequent use with BALSAC as well as with other professional visualization programs (LATUSE, PLOT3D, etc.). This includes encapsulated color PostScript format for generating structure graphics. BALSAC PostScript files are written specifically to maximize readability and enable easy editing to further modify/embellish structure plots. Among other applications, BALSAC/CLUSTER is particularly useful to - inspect and analyze local geometries and symmetries of any atom cluster such as - molecules, clusters, - finite sections of crystal lattices, allowing to postprocess structures generated with BALSAC/LATTICE by manipulating (adding/moving/hiding) single atoms or groups of atoms - surfaces, - interfaces; - explore possible atom clusters for structure determinations; - evaluate structural relationships qualitatively and quantitatively: bonding, interatomic distances, bond angles, atomic coordinates, etc; - generate instructive (color) graphics of complex structures presentations and publications: 3-dimensional structures with any viewing geometry including red/blue or full color stereo views. Further, color and gray scale PostScript output is possible allowing high quality prints on PostScript laser printers to be used for publications. next, previous Section / Table of Contents / Index