Toward a Complete Theory of Crystal Vibrations
electron–phonon problem is easily formulated. First, one considers an arrangement of massive point charges representing electrons and atomic nuclei. Second, one lets these charges evolve under Coulomb’s law and [...] that can be solved on today’s computers. One way to reduce the complexity of the problem is to step back from the picture of individual particles in favor of one of effective quasiparticles specific to [...] phonon: instead of focusing on the atomic nuclei that could, in principle, be located anywhere in space, one considers their collective vibration about their positions in a predefined crystal structure. Scientists