Effective phonon treatment of asymmetric interparticle interaction potentials

Abstract

We propose an effective phonon treatment in one dimensional momentum-conserved lattice system with asymmetric interparticle interaction potentials. Our strategy is to divide the potential into two segments by the zero-potential point, and then approximate them by piecewise harmonic potentials with effective force constants ${\tilde{k}}_L$ and ${\tilde{k}}_R$ respectively. The effective phonons can then be well described by ${\omega }_c=\sqrt{2({\tilde{k}}_L+{\tilde{k}}_R)}$. The numerical verifications show that this treatment works very well.

5 pages, 4 figures