STOs density functional theory

CEMS = conversion electron Mossbauer spectroscopy DFT = density functional theory EFG = electric field gradient EPR = electron paramagnetic resonance ESEEM = electron spin echo envelope modulation spectroscopy GTO = Gaussian-type orbitals hTH = human tyrosine hydroxylase MIMOS = miniaturized mossbauer spectrometer NFS = nuclear forward scattering NMR = nuclear magnetic resonance RFQ = rapid freeze quench SAM = S -adenosyl-L-methionine SCC = self-consistent charge STOs = slater-type orbitals TMP = tetramesitylporphyrin XAS = X-ray absorption spectroscopy. 

TABLE 4.7 The Same Quantities of Table 4.6 As Computed Within Various Ab Initio Approaches By Density Functional Theory Without Exchange-Correlation (noEX-C), and With B3-LYP, B3-PW91, and Becke97 Exchange-Correlations, and by Hartree-Fock method. All With Minimal (STO-3G) Basis Sets (Putz, 2010a)... 

Two other types of basis set that have been used successfully in hfs calculations are Chipman s contracted [3s,2p] bases, and basis sets based on Slater type orbitals (STOs). The former of these is mainly used in single excitation configuration interaction (CIS) calculations, and are based on a very fortuitous cancellation of errors between method and basis set. The performance of the CIS/[3s,2p] approach lies within 20-25% of experiment. One should recall, though, that once we go to larger molecular systems, the CIS method becomes computationally very demanding, STOs have mainly been used in semiempirical INDO hfcc calculations (STO-SG) and in the density functional theory (DFT) studies of Ishii and Shimitzu (STO-6G). The number of hfcc studies using these basis sets at the ab initio or DFT levels is however to date very limited. 

There is probably no other branch of computational chemistry that arouses such strong emotions as semiempirical molecular orbital (MO) theory. Early controversies between the Dewar and Pople groups about the relative merits of MINDO/3 and HF/STO-3G calculations set the scene for a schism between ab initioists" and semiempiricists that remains in a weakened form today. Perhaps symptomatic of this schism is the controversy that raged when density functional theory (DFT) methods began to make inroads into chemistry as to whether they are ab initio (good) or semiempirical (bad). The facts, also presented by the semiempirical articles in this work, are a little different. 

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