 # [lammps-users] density of states

Hello everyone,

Does anyone have experience in calculating the density of states (DOS) from the velocity autocorrelation function (VACF)? The DOS is defined as the fourier transform of the VACF from

gw = integral (cos(wt)*VACF(t)dt)

however when I use a 1D FFT algorithm the DOS has both real and imaginary components as the result of the transform. Here’s the question that I have: is the DOS the magnitude of the transform? the magnitude squared? or just the real part (because the expression of the transform has the cos(wt) term).

Thanks
Jaime Sanchez

Hello everyone,

Does anyone have experience in calculating the density of states (DOS) from the velocity autocorrelation function (VACF)? The DOS is defined as the fourier transform of the VACF from

gw = integral (cos(wt)*VACF(t)dt)

however when I use a 1D FFT algorithm the DOS has both real and imaginary components as the result of the transform. Here’s the question that I have: is the DOS the magnitude of the transform? the magnitude squared? or just the real part (because the expression of the transform has the cos(wt) term).

Thanks
Jaime Sanchez