My Community

Hello,

I checked the zero-point vibration frequency and energy in OUTCAR.

For example:
grep 2PiTHz OUTCAR
1 f = 20.900983 THz 131.324750 2PiTHz 697.181730 cm-1 86.439549 meV
........

I did a simple calculation: 0.5*h*v=0.5*4.136*10**-15*20.9*10**12=0.043 eV. It is not consistent with the last column energy output. This means the VASP output on energy is h*v, not 0.5*h*v. However, zero point energy for each mode is defined as 0.5*h*v. Am I correct?

Thanks!

Yep. Correct. So the total zero point vibrational energy is the sum of all the energy of all modes (minus 3 for translation). For proper handling of those see Wilson, Decious and Cross.

Cheers,

alex