Quantum-chemical Dynamics with the Slater-Roothaan Method

Quantum-Chemical Dynamics with the Slater-Roothaan Method 

Theoretical Chemistry Section, Code 6189, US Naval Research Laboratory, Washington, DC 20375, dunlap nrl.navy.mil 

Schwarz [5] found the values of that proportionality constant, a, which give the HF energy of the atom for each element. Any general method capable of using various a is called an Xa method. Any such method that uses Schwarz values of a can be said to be variational, if variational is taken to mean bounding 

Schwarz values of a turn out to lie between Slater s value of one and the Gaspar-Kohn-Sham (GKS) value of 2/3, as would those of a method constructed to give the total nonrelativistic atomic electronic energy. All values are used in the following spin density-functional expression for the exchange and correlation (XC) energy, 

Similarly, expanding the KS potential in an LCAO expansion makes molecular density-functional calculations practical [9]. For metals and similar crystalline solids, it is best to expand the Kohn-Sham potential in momentum space via Fourier coefficients. For molecular solids various real-space method are under investigation. For molecules studied with the big, well-chosen Gaussian basis sets of quantum chemistry, it is undoubtedly best to expand the KS potential in linear-combination-of-Gaussian-type-orbital (LCGTO) form [10]. 

---