Proceedings of the First Donegani Scientific Workshop on Strategies for Computer Chemistry : October 12–13, 1987

Front Matter....Pages i-vi Preface....Pages 1-2 Welcome Address....Pages 3-3 The Why’s of this Workshop....Pages 5-11 Development of potential energy functions for use in conformational analysis....Pages 13-29 Theoretical Studies of the Energetics and Dynamics of the Aqueous and Ionic Environment about Proteins: Crystals of Streptomyces Griseus Protease A....Pages 31-32 Bond lengths in transition structures and intermediates of cycloaddition reactions....Pages 33-44 Some Aspects of Computational Polymer Quantum Chemistry....Pages 45-77 Ab Initio Configuration Interaction Study of Electronic and Geometric Structure of Alkali Metal Clusters....Pages 79-91 “WIZARD: Artificial Intelligence and Conformational Analysis”....Pages 93-107 State of the Art in Vibrational Dynamics of Large Molecules....Pages 109-117 Density functional theory and first-principles pseudopotentials: two important tools in solid-state theory....Pages 119-160 Autodeductive Modeling and Optimization in Chemometrics....Pages 161-177 Statistical Distribution of Molecular Conformations and Its Application in QSAR Research....Pages 179-191 Molecular Chain Flexibility and Phase Transitions in Polymers....Pages 193-211 General Aspects of Computer-Aided Synthesis Planning....Pages 213-226 Detection and Structural Description of the Deepest Minima in a Potential Energy Hypersurface....Pages 227-243 Monte Carlo Simulation of the Solvation of a Ribonucleotide....Pages 245-249 Round Table Discussion on The Organization of a Molecular Modeling Group in a Chemical Industry....Pages 251-263 Back Matter....Pages 265-265 Cycloadditions are a very important class of reactions, which can be 1 used to obtain compounds of various ring sizes • Although these ,2 react? been largf: nvnntigated expnnivnntntit consi:fn ee f, :~oversy still fgeir mechanism, A reaction gene' ves the formaci new (J bonds between the reactants at the expense of n bonds. For such processes it is possible to postulate three different mechanisms: i) a synchron.ous concerted approach involving a cyclic transition state (TS) new bonds formed extent: ii)a neynchronous co:,:':" m:"chanism in whict fWO disticc to changes in e:f,me occurring the reactants and the single TS and the others mainly between the TS and products. iii) a two-step process, which occurs in two kinetically distinct steps via a ghnntical intermedintn Renect! gene computed the petential enerse or the ies of prototype tion reaction:f 4a i) the [2+2] cycloadditions H2C=CH2 + H C=CH , H C=O + H C=O,':b 2 2 2 2 H2 = 2 + O=O:4c C CH ii) the 1,3 dipolar cycloaddition HCNO + HC=CH, HCNO + H2C=CH2, H2CNHO 4d + H2C=CHd' 4e iii) cgdoaddition H C=CH • 2 2 have been potential enenpd th (STO-3G)5 ab-ini techniques f:ntcnged (4-31G)6 basis sets. All critical points have been fully optimized 7 using MC-SCF gradient techniques and characterized by diagonalizing 35 the related Hessian matrices computed using finite differences