I have been working on a system that consists of C, H, N, O. Vibrational properties have been calculated using CASTEP. while doing the analysis of these results, I have observed there are no atomic vibrations, but the direction of the force can be seen. In detail, the atoms are static with forces and at high frequency with high intensity, vibration can be noticed(very very slow). Why is this happening? Is it material propertie, I don't understand.