The external vibrations and the orientational disorder in solid C-60 were investigated at temperatures both above and below the disordering transition using neutron scattering experiments on a single crystal, and computer simulations based on a newly developed split-bond-charge model. A brief account is presented.

AbstractA model for calculating the statics and dynamics of a surface of a molecular crystal is presented. The (001) surface of naphthalene is chosen. The potential function used is the 6‐exp non‐bonded atom‐atom function, which has gained success in lattice dynamics. Surface layers of different thicknesses are investigated, all indicating that the third layer deep has a maximum binding energy. A slab of twelve layers thickness is used for the dynamics calculation, which shows clear evidence of surface modes. These are in general of lower frequencies than the bulk modes. The frequency distributions presented are divided into translational and librational parts, showing more clearly the nature of the surface modes.

Raman scattering measurements of the external vibrations in (NH 4 ) 2 CuCl 4 · 2 H 2 O are analysed on the basis of a rigid molecular–ion model involving a crystal potential that allows for pairwise interaction between atoms. Lattice stability is used as an important criterion in obtaining the parameters of the potential.

physica status solidi (b)Volume 95, Issue 2 p. K99-K102 Short Note Rotational invariance and stability constraints on the potential function in the external mode formalism S. L. Chaplot, S. L. Chaplot Nuclear Physics Division, Bhabha Atomic Research Centre, Bombay Search for more papers by this authorV. C. Sahni, V. C. Sahni Nuclear Physics Division, Bhabha Atomic Research Centre, Bombay Search for more papers by this authorK. R. Rao, K. R. Rao Nuclear Physics Division, Bhabha Atomic Research Centre, Bombay Search for more papers by this author S. L. Chaplot, S. L. Chaplot Nuclear Physics Division, Bhabha Atomic Research Centre, Bombay Search for more papers by this authorV. C. Sahni, V. C. Sahni Nuclear Physics Division, Bhabha Atomic Research Centre, Bombay Search for more papers by this authorK. R. Rao, K. R. Rao Nuclear Physics Division, Bhabha Atomic Research Centre, Bombay Search for more papers by this author First published: 1 October 1979 https://doi.org/10.1002/pssb.2220950241Citations: 5 Bombay-400085, India. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat References 1 G. Venkataraman and V. C. Sahni, Rev. mod. Phys. 42, 409 (1970). 10.1103/RevModPhys.42.409 Web of Science®Google Scholar 2 K. R. Rao, S. L. Chaplot, P. K. Iyengar, A. H. Venkatesh, and P. R. Vijayaraghavan, Pramǎna 11, 251 (1978). 10.1007/BF02848189 CASWeb of Science®Google Scholar 3 H. A. Rafizadeh and S. Yip, J. chem. Phys. 53, 315 (1970). 10.1063/1.1673783 CASWeb of Science®Google Scholar 4 G. S. Pawley, phys. stat. sol. 20, 347 (1967). 10.1002/pssb.19670200135 CASWeb of Science®Google Scholar 5 M. Born and K. Huang, Dynamical Theory of Crystal Lattices, Oxford Univ. Press, Oxford 1954. Google Scholar 6 S. L. Chaplot and V. C. Sahni, to be published. Google Scholar 7 M. L. Bansal, V. S. Sahni, and A. P. Roy, J. Phys. Chem. Solids, in the press. Google Scholar Citing Literature Volume95, Issue21 October 1979Pages K99-K102 ReferencesRelatedInformation