PHYSICAL REVIEW B
CONDENSED MATTER
and MATERIALS PHYSICS
Editor Associate Editors Assistant Editors
PETER D. ADAMS PATRICK BOUCHER ANTHONY M. BEGLEY
ALLEN GOLAND KELVIN G. LYNN G.M.S. LISTER
MYRON STRONGIN MICHAEL WEINERT
Senior Assistants to the Editor Assistant to the Editor
GEORGE MICHEL J.C. WHITE DANIEL T. KULP
R. MARK WILSON
EDITORIAL BOARD
Term ending 31 December 1998 Term ending 31 December 1999 Term ending 31 December 2000
NEIL ASHCROFT S. JAMES ALLEN HIDETOSHI FUKUYAMA
D.E. ASPNES ALLEN M. GOLDMAN PATRICIA M. MOONEY
C.W.J. BEENAKKER JOHN E. INGLESFIELD J.B. PENDRY
CHRISTIAN MAILHIOT JOHN J. QUINN JOSE A. RIERA
FRANS SPAEPEN B. SRIRAM SHASTRY
Published through the Manuscripts may be submitted electronically if in appropriate format
American Institute of Physics (see http://publish.aps.org/ESUB/ or inquire at prbtex@aps.org).
by Alternatively, send three copies to the Editorial Office. Submission is
The American Physical Society a representation that the manuscript has not been published previously
_________ and is not currently under consideration for publication elsewhere.
A signed APS copyright-transfer form (effective only on acceptance for
publication) must be provided; the form appears at the end of the 1
September 1997 issue of Physical Review Letters and is available on the
APS World Wide Web server. Information for contributors may be found in
the January and July issues.
President
ANDREW M. SESSLER To support wide dissemination of research results, we request payment
of a publication charge of $75 per page plus a $75 abstract charge. For
President-Elect properly prepared electronic submissions, no payment of charges is
JEROME I. FRIEDMAN requested. Acceptable formats are REVTeX (preferred), LaTeX, Harvmac,
plain TeX; PostScript figures. Reprints are offered for sale to authors.
Vice-President
JAMES S. LANGER
For information about subscription prices and about the online version
Executive Officer of the journal, see the APS Web server, or inquire at assocpub@aps.org.
JUDY R. FRANZ Member inquiries regarding subscriptions, renewals, address changes,
missing or damaged copies, microfilm and single-copy orders should be
Treasurer addressed to the APS Membership Department, One Physics Ellipse, College
THOMAS J. MCILRATH Park, MD 20740-3844.[phone:(301)209-3280; fax:(301)209-0867; e-mail:
Editor-in-Chief membership@aps.org]. Nonmembers: should address subscription inquiries
MARTIN BLUME to the AIP Circulation and Fulfillment Division,500 Sunnyside Boulevard,
_________ Woodbury, NY 11797-2999 [phone:(516)576-2270 or (800)344-6902;
fax:(516)349-9704; e-mail: subs@aip.org]. For address changes please
Editorial Office: send both old and new addresses, and, if possible, include an address
stencil imprint from the mailing wrapper of a recent issue; allow six
The American Physical Society weeks advance notice.
1 Research Road Box 9000
Ridge, NY 11961-9000
Phone: (516)591-4020 Copyright 1997 by The American Physical Society
Fax: (516)591-4141
Permission to quote excerpts or to reprint any figures or tables
should be obtained directly from an author. The American Physical
Email: prb@aps.org Society for its part hereby grants permission to quote excerpts and
Web: http://publish.aps.org/ reprint up to 25 figures and/or tables from its journals with
Submissions: prbtex@aps.org acknowledgment of the sources. Requests for permission to reprint in
or one publication more than 25 figures and/or tables from the totality
http://publish.aps.org/ESUB/ of APS journals must be made in writing to the Associate Publisher
(see address below). A $10.00 fee per figure and/or table in excess
of 25 will be charged. Individual teachers, students, researchers, and
libraries in non-profit institutions acting for them are permitted to
make hard copies of articles for use in teaching or research, provided
such copies are not sold. Copying of articles for sale by document
delivery services or suppliers, or beyond the free copying allowed above,
is permitted against payment of a copying fee. The current copying fee
is $15.00, per article, per copy. Express permission of APS is not
required, except for purposes stated below, provided that the fee is paid
through the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive,
Danvers, MA 01923. Contact the CCC for information on how to report
Production and distribution by copying and remit payments. Reproduction in a reprint collection, or
American Institute of Physics for advertising or promotional purposes, or republication in any form
500 Sunnyside Blvd. requires permission of one of the authors and a license from APS. Such
Woodbury, NY 11797-2999 a license must be sought from Mina Chung, Associate Publisher, The
Phone:(516)576-2200 American Physical Society. One Physics Ellipse, College Park, MD
Fax:(516)349-1802 20740-3844. Permission from the author must be sought and obtained from
Email: prb@aip.org him or her directly.
Web: http://www.aip.org/ Physical Review B (ISSN:0556-2813; CODEN PRVCAN; printed in USA) is
published once a month (on the 1st of each month) by The American
Institute of Physics. Periodicals postage ratesare paid at Woodbury, NY,
and additional mailing offices.