Does amorphous solids support phonons or nomal modes of vibration.?? Can we apply the concept of phonons and Debye Model in case of amorphous and poly-crystalline solids?? http://en.wikipedia.org/wiki/Phonon http://en.wikipedia.org/wiki/Debye_model The links I have attached above discusses only about quantization of normal vibrational modes in case of monocrystals. But, in real world most objects which we see around seems to be appearing polycrystalline(i.e. with grains and grain boundaries) or amorphous. So,how can we apply highly simplified concepts of phonons and debye model in case of such non-crystalline objects...??? "Does an amorphous solid also has normal modes of vibrations of atoms/molecules just like crystals do have...???" Please answer me as simple as possible as I am not an expert in this field.This question is not for homework,the question was born just out of curiosity... I have already searched about this matter on google but I did not find appropriate material,rather the material which I explored contained too high level mathematics which is out of my mind's regime. Please help by answering the basic concept and being as simple as possible.. "THANKS FOR READING THIS THREAD"