Computer graphics and graphical user interfaces as tools in simulations of matter at the atomic scale

The role of computer graphics in different aspects of simulating matter on the atomic scale is discussed. The computer graphics is useful in specifying and examining chemical structures, since it is nowadays possible to study––with density functional theory––complex systems containing up to a few hundreds in-equivalent atoms. Furthermore, computer graphics is also an indispensable tool in analysing computed data and facilitates interpretation of results. In this context XCrySDen (http://www.xcrysden.org/) is presented, a crystalline- and molecular-structure visualisation program, which aims at display of isosurfaces and contours, which can be superimposed on crystalline structures and interactively rotated and manipulated. Another aspect of computer utilisation in simulations that takes advantage of the computer’s graphics capabilities, is that it provides intuitive graphical user interfaces for the simulation setup. It is demonstrated how such interfaces are easily built using the developed GUIB software (http://www-k3.ijs.si/kokalj/guib/).