First we prove this relation in the classical mechanical way.
If it can be proved, we can use this theorem in the various Bohr model molecules.
We define the scalar value (Cvir), as follows.
Eq.2 means the sum of the each particle's dot product of the momentum (pi) and the position (ri).
( pi means the momentum vector of the i th particle. )
We can suppose the "arbitrary" particle's number (i = 1,2,3..) in Eq.2.
(We can use the Virial theorem in the system of many nuclei and electrons such as molecules.)