Direct calculation of electron density in density-functional theory: Implementation for benzene and a tetrapeptide

A recently developed approach for the direct calculation of electron density is implemented for polyatomic molecules: benzene and a tetrapeptide with four glycine residues. The method uses the density as the basic variable, divides a system into subsystems, and determines the density for each subsystem. It is found that the method is capable of describing the electronic structure with accuracy comparable to the Kohn-Sham method. This substantiates the hope for ab initio calculations of large systems beyond the reach of conventional methods.