Nonlocal density functional calculations: Comparison of two implementation schemes

We have carried out nonlocal density-functional calculations of bond dissociation and isomerization energies of several polyatomic molecules in two schemes. In the first scheme, the nonlocal energy functional is incorporated into the optimization of both the electronic and nuclear degrees of freedom. In the second scheme, the nonlocal energy functional is only included in a non-self-consistent fashion in which we just use the molecular geometry and electron density determined by the corresponding local density calculations. Our study reveals that the differences of the energies are very small between these two schemes.