Gaussian09 prints coordinates where the local coordinate system as center at
$C = (\Sigma n_i*X_i)/(\Sigma n_i)$
where $n_i$ is the Mass Numer of the atom. However, the Mass Number is not actually the mass of the nucleus. If we instead choose $m_i$, the true mass of each atom, as the weighting factor, we do not get the origin as the center of mass.
Is it ok to choose the origin that Gaussian09 gives us as the center of mass? Why or why not?