Figure 1 (IMAGE) Science China Press Caption (a) linear phonon dispersion based on acoustic-elastic-wave assumption, (b) sine phonon dispersion considering the periodic boundary condition, (c) lattice standing wave (top) and traveling wave (bottom). Credit ©Science China Press Usage Restrictions Use with credit. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.