Density-matrix-power functional: Performance for finite systems and the homogeneous electron gas

An exchange-correlation energy functional involving fractional power of the one-body reduced density matrix is applied to finite systems and to the homogeneous electron gas. The performance of the functional is assessed for the correlation and atomization energies of a large set of molecules and for the correlation energy of the homogeneous electron gas. High accuracy is found for these two very different types of systems.