Oscail X Windows based software for Molecular Modelling and Crystallography
from Patrick McArdle, National University of Ireland, Galway.

Oscail provides a PC windows based system for the study of molecules and crystals which is easy to use, has high quality graphics and is "academic free".   Oscail Tutorials are available.

Molecular Modelling

Molecular modelling is provided by Moilin, which operates under Oscail, and which drives Tinker (mm2/mm3), Mopac (AM1 etc.), Gamess (AM1 etc.) and ICONC (extended Huckel for t-metals)



Oscail provides the following facilities: (Lite version includes functions in bold)

(1) Data Reduction including PSI scans (CAD4)
(2) Space Group Determination
(3) Structure Solution
(4) Structure Refinement
(5) Absorption Correction (PSI Scans and Analytical Correction)
(6) Structure Visualization and Editing
(7) Hardcopy in several formats including direct printing
(8) High quality rendered pictures and movies
(9) Powder pattern simulation
(10) File format conversion

All of the components of the system are controlled by Oscail and help is provided for all of the programs. The excellent text editor PFE and the very powerful graphics viewer IrfranView are incorporated into the system. Most operations are just mouse clicks. A brief summary of some of the systems features

Xcad – A data reduction program for CAD4 data provides a considerable amount of statistical information and data reduction may include PSI scans correction using up to ten profiles if ABSCALC is used.

Absen – The Space Group Determination program is useful from an educational point of view as it lists the special reflections in a way which makes clear the number of reflections on which each condition depends. Barcharts of Space Group frequencies on the CCDC data base at the end of 2000 are provided.

Abscalc - Makes psi-scans absorption correction on the CAD4 a simple task. It also helps with analytical absorption correction.

ORTEX – The visualisation and structure editing program can display and rotate up to 5,000 thermal ellipsoids in mono or stereo. The stereo can be red-green 3D or conventional. Hard copy output may be written in a range of formats (including HPGL) but may also be printed directly on the PC's printer. Direct picture import via the clipboard is possible into all versions of WORD.
This system provided the first Windows version of Raster-3D the Unix program developed by Ethan Merritt. The photorealistic pictures are provided in JPEG (with adjustable quality), TIFF, BMP and GIF formats. RASMOV can be used to make rendered movies.

It is often wise to check if a single crystal structure is applicable to a bulk sample. The powder software can convert a HKL file to a pattern with "powder profiles." These patterns are often indistinguishable from experimental ones.

This software uses SHELXS and SHELXL97/2 which are provided by Professor Sheldrick. These programs should only be used by registered SHELX users. A web tutorial which includes a worked example and ten data sets suitable for use in advanced undergraduate practicals is also available.