Recent developments in the phase space formalisms within density functional theory are discussed. The phase space distribution function corresponding to a ground state electron density, obtained through an entropy maximization procedure, leads to good quality momentum density and first order reduced density matrix. Calculations of Compton profiles and exchange energies with different kinetic energy functionals show interesting results.

The presentwork reports results of computational investigations of hydrogen bonding, with regard to the most common red shift in the vibrational frequency, as well as the less common blue shift in several hydrogen bonded systems. A few new correlations of the frequency shifts with the calculated electrostatic parameters are proposed, thereby generating new insight into both types of the frequency shifts. Thus, the frequency shifts in X—H—-Y hydrogen bonded systems at differentH—Ydistances are shown to correlate well with the Mullikencharges on H and Y, with the positive and negative charges on Y correlating with the blue and red shift of the frequency of X—H vibration, respectively. The role played by charge transfers at other parts of the interacting system is also discussed.