COMPUTER SIMULATION OF CRYSTAL PROJECTION AND DIFFRACTION PATTERN

Based on the gnomonic projections and on the rotational reciprocal coordi-nate axes,a computer program,written in BASIC,is compiled for the simulationof various kinds of projections and diffraction patterns of crystals.These includethe standard gnomonic and stereographic projections,the transmission and back-reflection Laue patterns and the electron diffraction patterns.The projections anddiffraction patterns of both matrix and twin can be drawn together.In the caseof electron diffraction,the pattern may contain spots on any reciprocal layer be-sides the zero one.It is shown that these projections and patterns can be conve-niently used for the indexing of the diffraction spots and the determination of thecrystal symmetry,the type of the twin and the orientation relationship betweenmatrix and twin.