Journal ArticleDOI
Development and use of quantum mechanical molecular models. 76. AM1: a new general purpose quantum mechanical molecular model
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In this paper, a new parametric quantum mechanical molecular model, AM1 (Austin Model l), based on the NDDO approximation, is described, in which the major weaknesses of MNDO, in particular failure to reproduce hydrogen bonds, have been overcome without any increase in computing time.Abstract:
A new parametric quantum mechanical molecular model, AM1 (Austin Model l), based on the NDDO approximation, is described. In it the major weaknesses of MNDO, in particular failure to reproduce hydrogen bonds, have been overcome without any increase in computing time. Results for 167 molecules are reported. Parameters are currently available for C, H, 0, and N.read more
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The determination of the crystal structure of anhydrous theophylline by X-ray powder diffraction with a systematic search algorithm, lattice energy calculations, and C-13 and N-15 solid-state NMR: A question of polymorphism in a given unit cell
Elaine D. L. Smith,Robert B. Hammond,Matthew J. Jones,Kevin J. Roberts,John B. O. Mitchell,Sarah L. Price,Robin K. Harris,David C. Apperley,Julian C. Cherryman,Robert Docherty +9 more
TL;DR: In this article, a systematic search of direct space was employed to assess every possible packing arrangement of the asymmetric unit within the experimentally determined unit cell within the pharmaceutical material anhydrous theophylline (3,7-dihydro-1,3-dimethyl- 1H-purine-2,6-dione).
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