Statistical Thermodynamics for Beginners TTTThhhhiiiissss ppppaaaaggggeeee iiiinnnntttteeeennnnttttiiiioooonnnnaaaallllllllyyyy lllleeeefffftttt bbbbllllaaaannnnkkkk Statistical Thermodynamics for Beginners Howard D Stidham University of Massachusetts Amherst, USA World Scientific Published by World Scientific Publishing Co. Pte. Ltd. 5 Toh Tuck Link, Singapore 596224 USA office: 27 Warren Street, Suite 401-402, Hackensack, NJ 07601 UK office: 57 Shelton Street, Covent Garden, London WC2H 9HE Library of Congress Cataloging-in-Publication Data Names: Stidham, Howard D., author. Title: Statistical thermodynamics for beginners / Howard D. Stidham (University of Massachusetts Amherst, USA). Description: Hackensack, NJ : World Scientific, [2016] | Includes bibliographical references. Identifiers: LCCN 2016040516| ISBN 9789813149922 (hardcover ; alk. paper) | ISBN 9813149922 (hardcover ; alk. paper) | ISBN 9789813149939 (pbk. ; alk. paper) | ISBN 9813149930 (pbk. ; alk. paper) Subjects: LCSH: Statistical thermodynamics. Classification: LCC QC311.5 .S485 2016 | DDC 536/.7015195--dc23 LC record available at https://lccn.loc.gov/2016040516 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. Copyright © 2017 by World Scientific Publishing Co. Pte. Ltd. All rights reserved. This book, or parts thereof, may not be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording or any information storage and retrieval system now known or to be invented, without written permission from the publisher. For photocopying of material in this volume, please pay a copying fee through the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, USA. In this case permission to photocopy is not required from the publisher. Typeset by Stallion Press Email: [email protected] Printed in Singapore Preface This book is intended to serve as a relatively thorough introduc- tion to statistical mechanics for interested students who can regard themselves as beginnersinthearea.Itisassumedthatthereaderhas an abiding interest in mathematics and physics, and has had intro- ductory courses in advanced calculus, thermodynamics, and quan- tum mechanics. The book is based on a series of notes developed over approximately 50 years of teaching the subject to first and sec- ond year graduate students and to some fortunate undergraduates. There is much more material than can be reasonably presented in one semester, developed bit by bit over the years by the artifice of reserving the latter part of the course for coverage of material not included in previous years. Thebookisorganizedbychapteronly,buthasanunstatedstruc- ture. The first 5 chapters are concerned with the fundamentals of statistical mechanics. The next 4 chapters are concerned with calcu- lation of thermodynamic properties from spectroscopic data. This is followed by three chapters on polymers of increasing difficulty. The chapter on excluded volume is presented near the research level. The remaining four chapters cover quantum statistics, adsorption, heat capacityofcrystals,andimperfectgasesandliquids,notinthisorder. Although thebook is intended as a textbook, thereare relatively few problems at the ends of the chapters. Some chapters have no prob- lemsatall.Thereasonforthisisthatgraduatestudentsareexpected v vi Statistical Thermodynamics for Beginners to do research, generally working in another field to which statistical mechanics is not directly applicable, and do not have much time to solve routine problems. In addition, there are many very good prob- lemsinotherbooksonstatisticalthermodynamics.McQuarrie’sbook is an especially rich source of endless problems, should an instructor feel motivated to augment the text. The problems given are largely intended to emphasize some point in the text. A close reading of the book will reveal the great debt owed T. L. Hill, W. H. Stockmayer, Marshall Fixman and E. A. DiMarzio. In particular, the lectures given by Marshall at Yale in 1965 resulted in my notes on which I based several developments in the text, notably the Gaussian probability for the infinite polymer chain, the transfer method in the helix-coil transition, and the argument for ensemble equivalence. It is probably impossible to surpass Hill’s Introduction to Statistical Thermodynamics, and this book does not try. But Hill’s book is out of print, and is no longer useful as a text- book since it is of undependable availability. There are a number of textbooks presently available, each with its own strengths and weak- nesses. This book is a unique addition, containing some material not easily available elsewhere. Any serious student of statistical mechanics will sooner or later run into a need to consult some of the classic works in the area. A brief list of some of the prominent books follows. In particular, the book by Mayer and Mayer has some surprising inclusions that are not often seen in modern applications, but deserve inspection. In his lectures on statistical mechanics at Yale in the 1960’s, Lars Onsager always came to lecture carrying a copy of Mayer and Mayer, which he never consulted, but which always occupied a prominent place on the lecture table. It is especially recommended. The list of books that should be available to a practicing statis- tical mechanician includes several of a mathematical nature. Those from my personal collection are: M. Abramowitz and I. A. Stegun, Nat’l Bur. Stds. AMS 55, 1964, th 5 Printing. J. H. Hildebrand, “Advanced Calculus for Engineers,” Prectice-Hall, New York, 1949. Preface vii L. B. W. Jolley, “Summation of Series,” Dover reprint. E. T. Whittaker, “Analytical Dynamics,: Dover reprint. E. T. Whittaker and G. N. Watson, “A Course of Modern Analysis,” th 4 Ed., Cambridge, 1927. In addition, there are a number of books on statistical mechanics that are useful. These include, but are not limited to, the following: W.Band,“Introduction toQuantumStatistics,” VanNostrand,New York, 1955. M. Born and K. Huang, “Dynamical Theory of Crystal Lattices,” Oxford, 1954. D. Chandler, “Introduction to Modern Statistical Mechanics,” Oxford, 1987. N.Davidson,“StatisticalMechanics,”McGraw-Hill,NewYork,1962. P. J. Flory, “Principles of Polymer Chemistry,” Cornell, Ithaca NY, 1953. R. H. Fowler and E. A. Guggenheim, “Statistical Thermodynamics,” Cambridge, 1939. J. W. Gibbs,“The Collected Works of J. Willard Gibbs,” Vols. I and II, Yale, 1948. D.terHaar,“ElementsofStatisticalMechanics,”Constable,London, 1954. nd D.ter Haar, “Elements of Thermostatistics,” 2 Ed.,Holt, Rinehart and Winston, New York, 1966. T. L. Hill, “Statistical Mechanics,” McGraw-Hill, New York, 1956. T. L. Hill, “Thermodynamics of Small Systems,” Benjamin, New York, 1963. T. L. Hill, “Introduction to Statistical Thermodynamics,” Addison- Wesley, Reading, MA, 1960. T. L. Hill, “Cooperativity Theory in Biochemistry,” Springer Verlag, New York, 1985. J. O. Hirschfelder, C. F. Curtiss and R. B. Bird, “Molecular Theory of Gases and Liquids,” Wiley, New York, 1954. L. D. Landau and E. M. Lifshitz, “Statistical Physics,” Pergamon, London, 1958. viii Statistical Thermodynamics for Beginners J. E. Mayer and M. G. Mayer, “Statistical Mechanics,” Wiley, New York, 1940. D. A. McQuarrie, “Statistical Mechanics,” Harper and Row, New York, 1976. D. A. McQuarrie, “Statistical Thermodynamics,” Harper and Row, New York, 1973. L. K. Nash, “Elements of Statistical Thermodynamics,” Addison- Wesley, Reading MA, 1968. G. S. Rushbrooke, “Introduction to Statistical Mechanics,” Oxford, 1949. E. Schrodinger, “Statistical Mechanics,”Cambridge, 1960. J. C. Slater, “Introduction to Chemical Physics,” McGraw-Hill, New York, 1939. nd M. Toda, R. Kubo, N. Saito, “Statistical Physics,” 2 Ed., Springer Verlag, Berlin, 1983, 1992. R. C. Tolman, “Principles of Statistical Mechanics,” Oxford, 1938. G. H. Wannier, “Elements of Solid State Theory,” Cambridge, 1959. One important area not covered in the first edition of this book is phase transitions. The interested reader may find it useful to consult good textbooks of physical chemistry for the groundwork and then graduate to such books as the following: H. E. Stanley, “Introduction to Phase Transitions and Critical Phe- nomena,”Oxford, 1971. J.M.Yoemans,“StatisticalMechanicsofPhaseTransitions,”Claren- don Press, Oxford, 1992. “New Kinds of Phase Transitions,” V. V. Brazhkin, S. V. Buldyrev, V. N. Ryzhov, H. E. Stanley, Eds., NATO Science Series, Kluwer, Dordrecht/Boston, London, 2002. Amherst, Massachusetts May 2016 Contents Preface v Chapter 1. Review of Classical Mechanics and Thermodynamics 1 Chapter 2. The Basis of Statistical Mechanics 19 Chapter 3. Steepest Descent 47 Chapter 4. Gaussian Distribution, Ensemble Equivalence and Fluctuations 61 Chapter 5. A Variational Principle, Phase Space, Classical Averaging and Ω 77 Chapter 6. Gases 91 Chapter 7. Homonuclear Diatomic Molecules 113 Chapter 8. Polyatomic Molecules 137 ix x Statistical Thermodynamics for Beginners Chapter 9. Residual Entropy and Chemical Equilibrium 165 Chapter 10. Polymers 183 Chapter 11. More Polymers 213 Chapter 12. Excluded Volume of Polymer Chains 239 Chapter 13. Imperfect Gases and Liquids 305 Chapter 14. Bose-Einstein, Fermi-Dirac and Boltzmann Statistics, Quantum Gas 341 Chapter 15. Adsorption 371 Chapter 16. Heat Capacities of Solids 431 Index 481