Tuyển tập các báo cáo nghiên cứu khoa học trên tạp chí khoa học vật lý quốc tế đề tài: LATTICE DYNAMICS AND NORMAL COORDINATE ANALYSIS OF HTSC Tl2Ba2Cu1O6 | Journal of Physical Science Vol. 17 2 27-35 2006 27 LATTICE DYNAMICS AND NORMAL COORDINATE ANALYSIS OF HTSC TLBaiCuiOô S. Mohan1 K. Sonamuthu2 and Sujin P. Jose1 1Annai Fathima College Madurai 625 706 India 2Raman School of Physics Pondicherry University Pondicherry 605 014 India Corresponding author smoh14@ Abstract The lattice dynamics of the high temperature superconductors Tl2Ba2Cu1O6 have been investigated on the basis of the three body-force shell model TSM . The various interactions between ions are treated in a general way without making them numerically equal. The phonon frequencies at the zone center of Brillouin zone are presented and the vibrational assignments are discussed. Further the normal coordinate calculation has also been employed to study the vibrational analysis of this compound. The normal coordinate analysis of the superconductor Tl2Ba2Cu1O6 has been calculated by using the Wilson s FG-matrix method which is useful for the confirmation of our present investigation. The vibrational frequencies and the potential energy distribution PED of the optically active phonon modes are also presented. Keywords lattice dynamics phonon frequencies Tl2Ba2Cu1O6 Raman and infrared spectroscopy 1. INTRODUCTION The study of the lattice dynamics of the high-temperature superconductors is of importance not only for the overall physical characterization of these compounds but also for an assessment of the role played by the phonons . the superconducting phenomenon. A lattice dynamical study requires the knowledge of the crystal structure and the particle interactions. Usually the crystal structure is determined using X-ray diffraction XRD . For particle interactions one has to use models which represent the characteristic of the electronic structure and its effect on ionic interaction in a relevant manner. In lattice dynamics the ionic interactions are expressed in terms of force constants. Cox et al. 1 have refined the structure of .
