My Community

does VASP output the amplitude of vibration in frequency calculations (ie the maximum displacement of each atom during vibration)? I recognize that the amplitudes are given by the eigenvectors of the Hessian matrix, but these vectors are normalized and thus they only give the relative displacements of each atom in the system rather than the absolute displacements. Does VASP output the true displacements as well?

no.

Do you mean eigenvectors that VASP provide to us is X= M^1/2*A?
A: the ion's real amplitude of mode

Thank you.