Basis LACVP

The reference 48 authors used an UB3LYP unrestricted DFT method. Jaguar 5.5 and Gaussian 03 software, beginning calculations with an LACVP (Fe)6-31G (rest) basis set. See Section 4.4.3.The researchers assumed a direct protonation mechanism involving a framework of amino acid residues... 

The 6-3IG basis set is presently available for first-row transition metals only (Sc-Zn). STO-3G and 3-2IG basis sets are also available for second-row metals (Y-Cd), but are not recommended for use with correlated models. The LACVP pseudopotential is available for all three transition series and PM3 parameterizations have been developed for most important metals in all three rows. 

Note that the LACVP pseudopotential reverts to the 6-3 IG basis set for non-metals. 

The calculations were performed in three steps. For each structure considered, a geometry optimization was performed using the hybrid density functional B3LYP method (21). For open shell systems unrestricted DFT was used. In this first step, a standard valence double zeta basis set (the lacvp basis set) was used. Since models including also second shell amino acid residues were used, a full geometry optimization is not possible. The second shell residues would then move in unrealistic ways. For this reason, one atom of each amino acid residue was frozen from the X-ray structure. This procedure has been found to work very well in previous studies (22,23). It might be thought that this... 

Here, we should comment on the inconsistency of the basis sets employed for geometries and magnetic interactionism and LC-coPBE/LACVP //LC-coPBE/chem. A most remarkable error in optimization calculations of LC-coPBE/chem is for the double-protonated state, in which the error is approximately 0.1 A as described above. This must be caused by the different levels of the basis sets for the Mn atoms triple-zeta + diffuse + polarization (TZ + d + p) quality function in the chem basis set and LANL-DZ in the LACVP basis set. Obviously, the interatomic (Mn-Mn) distances of chem are larger than the corresponding values of LACVP not only for LC-coPBE but also for all other XC functionals as shown in Fig. 26.3. A noteworthy point is that the chem basis set is a typical different basis... 

LACVP basis sets use 6-3IG for main group elements and the Hay-Wadt ECP for Ni Hay PJ, Wadt WR (1985) J Chem Phys 82 299... 

---