ORTEP, computer program

Fig. 7. Two conformations of the thiazolidine ring of a model penam. 6-Aminopeni-cillanic acid (6-APA) is used as an example. In the top conformer, Cj is flipped up, so the 2p and 3a substituents (CH, and COOH, respectively) are roughly axial. In the bottom conformer, Cj is flipped down, so that the 2(3 and 3a substituents are more nearly equatorial. Obviously, when the 2 and 3a groups are axial (equatorial), the 2a and 3p groups are equatorial (axial). The drawings were produced with the ORTEP computer program (Johnson, 1976).

Figure 3. Analcime. Apparent thermal-motion probability ellipsoids of the T and 0 atoms in the A structure and the displacements from the symmetrized position obtained by DLS. Ellipsoids are based on thermal parameters reported by Knowles, Rinaldi, and Smith (7) and are scaled to enclose 50% probability. The diagrams were generated with the aid of computer program ortep by C.K. Johnson...

Semi-empirical strain energy calculations for cyclooctane have been carried out by four groups 10-13,35-37) (Table 2). The perspective drawings 38) in Fig. 1 were drawn by the computer program Ortep 39) with the parameters calculated by Hendrickson, n) Table 2 gives dihedral angles, the sets of... 

The reader should now appreciate that the use of fractional atomic coordinates to arrive at molecular geometry is straightforward. This is evident on inspection of crystal structure determinations in the scientific literature. The effects of thermal motion and slight disorder are illustrated by use of the computer program ORTEP. The amplitudes of... 

ORTEP is an acronym for "Oak Ridge Thermal Ellipsoid Program," a computer program frequently used in structural analysis. The acronym is often used as a short label to indicate a drawing in which ellipsoids indicate the extent of thermal motions of the atoms. 

In 1965 there was described in the chemical literature a computer program called ORTEP that could be used to draw chemical stractures obtained from X-ray crystallography. It would draw a structure as a pair of stereographic projections, which made it easy to see structures in three dimensions (see Fig. 2.5). (If the reader is not able to see Figure 2.5 in three dimensions, please look at the instructions given in the Appendix... 

Figs, lla-c. Stereoscopic drawing of the various conformations of a proline dimer. The diagrams were obtained using the computer program ORTEP of Johnson [27]. (a) cis conformation, (b) trans conformation, (c) cis conformation. 

Least-squares computations were performed with a local version of ORFLS (37), with the X-RAY system (33), or with the CRYM system (39). Molecular plots were produced with ORTEP (40). Calculations for the neutron structures were carried out on CDC 7600 and CDC 6600 computers at Brookhaven National Laboratory, making use of programs described by Berman et al. (41). 

All calculations were done on a CDC-6600 computer, using unpublished versions of least-squares, FORDAP, and other programs written and revised by A. Zalkin. All drawings were done using ORTEP, by C. K. Johnson, Oak Ridge National Laboratory, June 196S. 

---