HCTH functional

CC-VSCF was also used for computing anharmonic vibrational spectra from DFT potentials [103,104], The most accurate spectroscopic results are obtained from the hybrid functionals B97 [105] and B3LYP [106], of the non-hybrid DFT functionals, HCTH [107] seems superior to BLYP [108], The spectroscopic accuracy of B97 and B3LYP was about equal to that of MP2. 

Leonard et cd. [105] reported ab initio DMSs of H2CS computed using the functional HCTH and the TZ2P basis set. The x, y and z components of the ab initio dipole moment functions were approximated by third order polynomial expansions in internal displacement coordinates for the six degrees of freedom as follows ... 

For the hydrogen bonded complexes (FH)2, (HC1)2, (H20)2, FH-CO, FH -OC, FH -NH3, CIH- NH3, OH2-NH3, and H30+—H20, with binding energies ranging from 1.7 kcal/mol (FH-CO) to 32.9 kcal/mol (H30+—H20), Tuma, Boese, and Handy, 1999, compared results of several density functional methods with high level conventional wave function based data. With the exception of the HCTH functional, all functionals were found to over-... 

Aside from the well-known LDA (local density approximation (26, 27) BLYP (Becke-Lee-Yang-Parr (28, 29)) and B3LYP (29, 30) functionals, we considered the more recent B97-1 functional (which is a reparametrization (31) of Becke s 1997 hybrid functional), the B97-2 functional (32) (a variation of B97-1 which includes a kinetic energy density term), and the HCTH-407 (33) functional of Boese and Handy (arguably the best GGA functional in existence at the time of writing). The rationale behind the Wlc (Weizmann-1 cheap) approach is extensively discussed elsewhere. (34,35) For the sake of self-containedness of the paper, we briefly summarize the steps involved for the specific system discussed here ... 

The B3LYP B97-n, and HCTH/407 compare quite well to experiment and Wlc it should be recalled that all four functionals were wholly or partially fitted to atomization energies. The B97-1 result in fact is identical to Wlc, while the pure DFT HCTH/407 functional does surprisingly well. 

HCTH Hamprecht. Cohen. Tozer. and Handy GGA exchange-coiTelation functional based on a reoptimization/extension of empirical parameters in B97 and a removal of HF exchange. Now a family of functionals with optimizations over different numbers of test-set molecules, typically denoted HCTH/w where n is the number of molecules in the test set, e.g., HCTH/93, HCTH/120, HCTH/147, and HCTH/407. Hamprecht, F. A., Cohen, A. J., Tozer, D. J., and Handy, N. C. 1998. 7. Chem. Phys., 109, 6264. (Most recent refinement, Boese, A. D., Martin, J. M. L., and Handy, N. C. 2003. 7. Chem. Phys., 119, 3005.)... 

Studies using the GGA- (BLYP) and hybrid- (HCTH, B3LYP, B97, B97-1) functionals combined with the Sadlej s basis set demonstrate that all considered functionals also lead to very reasonable dipole moments for a representative a set... 

---