THE subject of crystal dynamics, which is concerned with the vibrational movement of atoms in the solid state, is now of respectable antiquity. The classic papers are perhaps those of Einstein1, Debye2 and Born and v. Kármán3, which deduce the specific heat of metals from the vibrational energy of the crystal lattice. The whole subject has recently received a new interest and stimulus by the discovery that the thermal vibrations of the atoms of a crystal produce measurable effects in the background of X-ray diffraction patterns. The normal Bragg-Laue diffraction pattern of a crystal is characteristic of its geometry: the thermal motion of the atoms appears as a pattern in the background of the diffraction photographs. This is a subject which evidently has wide ramifications, and in fact must ultimately affect every branch of physics concerned with the solid state of matter. The experimental and theoretical development of the subject have been ably summarized by Lonsdale4 and Born5.
Einstein, Ann. Phys., 22, 180 (1907).
Debye, Ann. Phys., 39, 789 (1912).
Born and v. Kármán, Phys. Z., 13, 297 (1912).
Lonsdale, Reports on Progress in Physics., 9, 256 (1943).
Born, Reports on Progress in Physics., 9, 294 (1943).
Raman and others., Proc. Indian Acad. Sci. Bangalore, 1–102 (1943).
Lederman, Proc. Roy. Soc., A, 182, 362 (1944).
Fermi and Rasetti, Z. Phys., 71, 689 (1931).