Computational Methods in Chemistry

Transcription

1 Computational Methods in Chemistry

2 THE IBM RESEARCH SYMPOSIA SERIES Computational Methods in Band Theory Editors: P.M. Marcus, J.F. Janak, and A.R. Williams Computational Solid State Physics Editors: F. Herman, N. W. Dalton, and T. R. Koehler Sparse Matrices and Their Applications Editors: D. J. Rose and R. A. Willoughby Complexity of Computer Computations Editors: R. E. Miller and J. W. Thatcher Associate Editor: J. D. Bohlinger Computational Methods for Large Molecules and Localized States in Solids Editors: F. Herman, A. D. McLean, R. K. Nesbet Ion Implantation in Semiconductors and Other Materials Editor: Billy L. Crowder Stiff Differential Systems Editor: Ralph A. Willoughby Optimal Estimation in Approximation Theory Editors: Charles A. Micchelli and Theodore J. Rivlin Topics in Surface Chemistry Editors: Eric Kay and Paul S. Bagus Advances in Digital Image Processing: Theory, Application, Implementation Editor: Peter Stucki The Physics and Chemistry of Liquid Crystal Devices Editor: Gerald J. Sprokel Computational Methods in Chemistry Editor: Joachim Bargon

3 Computational Methods in Chemistry Edited by Joachim Bargon IBM Research Laboratory San Jose, California PLENUM PRESS. NEW YORK AND LONDON

4 Libf'ery of Congress C.",loging in Publlcetion Oa'" Symposium on Compu"'tional Methods in Chemistry. Bad Nauenahr, Ger., Computational methods In chemistry. (The IBM rnearch sympolia IfIriBl) "Proceeding!! of the Symposium on Compu"'tlonal Methods in Chemistry, held in BIId Neuenehr, German Federal Republic, SeptlllTlbe\' 17-19, 1979." SponlOl1Id by IBM Germany. lneludes Index. 1. Spe(:trum analysis-de", processing-congresses. 2. Ouantum chllltlistry-oa'" processing-con,,_s. I. 8ergon, Jaochim. II. IBM Deutschland. III. Title. IV. Series: International BUlil"lllSS Meehines Corporation. IBM I'8IIIIrch symposia seriel ' ISBN-13: e-lsbn-13: : / Proceedings of the International Symposium on Computational Methods in ChlllTlistry, sponlol1id by IBM Germany and held in Bed Neuenehr. German Federal Republic, September 17-19, Cl1980 Plenum Press, New York Softcover reprint of the hardcover 1 st edition 1980 A Division of Plenum Publishing Corporation 227 West 1 7th Street, New York, N.Y All rights ntserved No Part of this book may be reproduced, stored in a retrieva' lynam, or transmitted, in any form or by any means, electronic, mactwtnicel, photocopying, microfilming, RlCording, or otherwl$e, without written permisiion from the Publisher

5 PREFACE The papers collected in this volume were presented at an international symposium on Computational Methods in Chemistry. This symposium was sponsored by IBM Germany and was held September 17-19, 1979, in Bad Neuenahr, West Germany. According to Graham Richards [Nature 278, 507 (1979)] the "Third Age of Quantum Chemistry" has started-;-where the results of quantum chemical calculations have become so accurate and reliable that they can guide the experimentalists in their search for the unknown. The particular example highlighted by Richards was the successful prediction and subsequent identification of the relative energies, transition probabilities and geometries of the lowest triplet states of acetylene. The theoretical predictions were based chiefly upon the work of three groups: Kammer [Chern. Phys. Lett. ~, 529 (1970)] had made qualitatively correct predictions; Demoulin [Chern. Phys. 11, 329 (1975)] had calculated the potential energy curves for the two lowest triplet states (3B and 3A) of acetylene; and Wetmore and Schaefer III [J. Chern. Phys. ~~ 1648 (1978)] had determined the geometries of the cis (3B and ~A ) and the trans (3B2 and 3A2 ) isomers of these two sta~es. Inua guided search, Wendt, Hunziker and Hippler [J. Chern. PHys. 70, 4044 (1979)] succeeded in finding the predicted near infrared absorption of the cis triplet acetylene (no corresponding absorption for the trans form was found, which is in agreement with theory), and the resolved structure of the spectrum confirmed the predicted geometries conclusively. This convincing success of quantum chemical predictions triggered our curiosity to assess the extent to which experimentalists, working in different fields of chemistry, could benefit from recent achievements of theoretical methods. At the same time, we wanted to inform the theoreticians about the current needs of the experimentalists. v

6 vi PREFACE The focus of this symposium was chiefly on two areas of chemistry, namely the computational progress in various kinds of spectroscopy (NMR, IR, ESR, PES, and Mass Spectrometry), and the recent achievements of quantum chemistry, sometimes called "Computer Chemistry" by the lectureres in this volume. Considerable time was spent during discussion periods to compare the strengths and weaknesses of semi-empirical versus ab initio methods when applied to problems of varying size and to properties of a different nature. In the chairman's opinion, it seems that both approaches will continue to co-exist, each taking their specific role. In the case of theoretical studies of chemical reactions, for example semi-empirical methods can provide an economical way to map out potential energy surfaces in a preliminary and crude form, perhaps by automatically forming energy gradients combined ~ith automated geometry optimization, followed by a refinement of all parameters with sophisticated ab initio methods in the areas of highest interst. A great number of theoretical and computational methods, customary in chemistry nowadays, had to be omitted or seriously neglected. Thus no Monte Carlo calculations were included not as the consequence of parochial thinking due to the casino next door, but rather because of the hopeless task to consider all of the known computational methods in chemistry within the framework of a coherent but limited symposium. The topics chosen here were considered to be of interest to a group of scientists whose bandwidth would overlap in the area of physical organic chemistry. Joachim Bargon IBM San Jose Research Laboratory Symposium Chairman Paul Schweitzer IBM Germany, Sindelfingen Symposium Manager

7 CONTENTS Setting up, Using, and Maintaining Computer Readable Spectra Compilations..... J. T. Clerc and H. Konitzer The Solution to the General Problem of Spectral Analysis Illustrated with Examples from NMR G. Binsch Determination of the Structures of Organic Molecules by Computer Evaluation and Simulation of Infrared and Raman Spectra.... B. Schrader, D. Bougeard, and W. Niggemann Phenomena in Photoelectron Spectroscopy and Their Theoretical Calculation... W. von Niessen, L. S. Cederbaum, W. Domcke, and J. Schirmer Novel Radical Ions: Generation and Properties. An Interim Report on PES and ESR Investigations H. Bock, G. Brahler, W. Kaim, M. Kira, B. Roth, A. Semkow, U. Stein, and H. Tabatabai Potential Surface Studies of Open Shell Systems... P. Bischof Computed Physical Properties of Small Molecules.. W. Meyer, P. Botschwina, P. Rosmus, H.-J. Werner Calculation of Electronically Excited States in Molecules: Intensity and Vibrational Structure of Spectra, Photochemical Implications... S. D. Peyerimhoff and R. J. Buenker

8 viii The Application of Ab Initio Quantum Chemistry to Problems of Current Interest Raised by Experimentalists P. S. Bagus, B. Liu, A. D. McLean, and M. Yoshimine Computer Chemistry Studies of Organic Reactions: The Wolff Rearrangement J. Bargon, K. Tanaka, and M. Yoshimine Computer Programs for the Deductive Solution of Chemical Problems on the Basis of Mathematical Models - A Systematic Bilateral Approach to Reaction Pathways.. I. Ugi, J. Bauer, J. Brandt, J. Friedrich, J. Gasteiger, C. Jochum, W. Schubert, and J. Dugundj i Recent Developments in Computational Chemistry in the U.S.: The NRCC (National Resource for Computation in Chemistry). W. A. Lester, Jr. Index CONTENTS