<Dl> <Dd> p i (X i) = e − E i k B T ∫ d X i e − E i k B T (\ displaystyle p_ (i) (X_ (i)) = (\ frac (e ^ (- (\ frac (E_ (i)) (k_ (B) T)))) (\ int dX_ (i) \, e ^ (- (\ frac (E_ (i)) (k_ (B) T)))))), </Dd> </Dl> <Dd> p i (X i) = e − E i k B T ∫ d X i e − E i k B T (\ displaystyle p_ (i) (X_ (i)) = (\ frac (e ^ (- (\ frac (E_ (i)) (k_ (B) T)))) (\ int dX_ (i) \, e ^ (- (\ frac (E_ (i)) (k_ (B) T)))))), </Dd> <P> In this section, and throughout the article the brackets ⟨ ⟩ (\ displaystyle \ langle \ rangle) denote the mean of the quantity they enclose . </P> <P> The internal energy of the system is the sum of the average energies associated with each of the degrees of freedom: </P>

How many vibrational degrees of freedom are there for nh3