NRCVAX – an interactive program system for structure analysis

Abstract

NRCVAX is a complete system ~af programs, covering all aspects of crystal structure analysis from data reduction to the presentation of results. The system, which is written in a 'neutral' Fortran 77, presently exists in two forms. The first runs on a VAX computer under VMS, on an 80386 PC under UNIX and under IBM VM/CMS and MVS/TSO. The second is an adaptation which runs on PC-XT, AT, PS/2 and comparable microcomputers under MS-DOS. The two versions differ somewhat in structure, but very little in code, operation or functionality except for the graphics. The many options of the programs can be selected in a highly interactive manner and because of this the System is very flexible. Most options are assigned default values, however, and it is usually safe to run the routines with a minimum of user input using the defaults. The system will accept data from a wide variety of sources and has interface routines for several other systems. Graphics in the VAX/UNIX version are based on the widely available Tektronix 4000 series protocol, while the microcomputer version supports most common display adapters. It is also possible to prepare files for a variety of plotters, dot-matrix printers and laser printers.• Source code is distributed and it should not be difficult to adapt the system to any computer with virtual memory and a Fortran 77 compiler.

Stereochemistry of crown ethers, X-ray crystallographic structures, solid phase 13C NMR, and solution conformational equilibria in cis-syn-cis dicyclohexano-15-crown-5 ether and its sodium thiocyanate complex

“…As the space group of 1 could be Pbnm, cell symmetry was checked with the program MISSYM, which finds all metric symmetry elements from the atomic coordinates of any crystal structure and builds the generators in the unit cell (17). In addition to the b and n glide planes perpendicular to the a and b axes respectively, MISSYM detected mirror symmetry perpendicular to the c axis of the unit cell.…”

“…Details of the structure refinement of 1 and D-map are given in Table 3. All computations were performed with the NRCVAX crystal package (17). The scattering curves were from the ~nternational Tables for X-ray Crystallography (1 8).…”

A Polymorph Lost and Found: The High‐Temperature Crystal Structure of Pentacene

“…Surface-tension effects may also play a role, because the 15.0 and 15.4 Å thin-film polymorphs are easily converted into pentacene-HT by being dipped into solvents such as ethanol, in which pentacene is not soluble. [26] Thin films often have a d-spacing of 14.5 Å, and hence most possibly crystallize in the metastable, pentacene-HT structure. Thin-film processing therefore has to take into account that an incomplete phase transformation might occur at higher temperatures, leading to large stress/strain fields in the films that will induce defect formation.…”

Organometallic oxides and sulfides: preparation of [(η-C5H5)Ti]5(μ3-S)6, [(η-C5H5)Ti]5(μ3-S)5(μ3-S2)(μ4-O), and(η-C5H5)2Ti(SH)(μ-O)Ti(η-C5H5)(μ-S)2- Ti(η-C5H5)2 by reductive aggregation of (η-C5H5)2Ti(SH)2 with zinc powder or

“…commodate such a large number of atoms. The latest version of NRCVAX (21), which was used for the refinement, accommodated the atoms but only allowed a block refinement.…”

“…Data were collected using the 8/28 scan method. Refinement used the NRCVAX suite of programs (21). The weighting scheme was of the form = I/(c(F)?…”