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Unformatted text preview: 1 CONDENSED MATTER PHYSICS 171.405 / 171.621 Instructor: N.P. Armitage Grader: Paula Mellado Fall 2007 Problem Set 5 Due to Graders mail box by Monday Dec. 10th ============================= Q 1: Kittel Problem 4.1 ============================= Q 1: Kittel Problem 4.3 ============================= Q 2: In class we solved the equations of motion for the linear diatomic chain and found two solutions for its atomic motion. These are referred to as acoustic and optical phonon branches. Two branches exist because we allowed motion in only one direction and there are two atoms per unit cell. In other words, for 1D motion, in order for there to be two branches there MUST be two different atoms per unit cell. In principle these two different atoms can differ in a variety of ways including having different masses only (for instance different isotopes), different charges only (different ions), both different masses and charges, or other distinctions....
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This note was uploaded on 12/06/2009 for the course PHYSICS 171.405 taught by Professor N.peterarmitage during the Fall '07 term at Johns Hopkins.
- Fall '07