AM1* parameters for phosphorus, sulfur and chlorine

Abstract

An extension of the AM1 semiempirical molecular orbital technique, AM1*, is introduced. AM1* uses AM1 parameters and theory unchanged for the elements H, C, N, O and F. The elements P, S and Cl have been reparameterized using an additional set of d orbitals in the basis set and with two-center core-core parameters, rather than the Gaussian functions used to modify the core-core potential in AM1. Voityuk and Rösch's AM1(d) parameters have been adopted unchanged for AM1* with the exception that new core-core parameters are defined for Mo-P, Mo-S and Mo-Cl interactions. Thus, AM1* gives identical results to AM1 for compounds with only H, C, N, O, and F, AM1(d) for compounds containing Mo, H, C, N, O and F only, but differs for molybdenum compounds containing P, S or Cl. The performance and typical errors of AM1* are discussed.

A semi-empirical molecular orbital study of freestanding and fullerene-encapsulated Mo nanoclusters

“…displacement of 0.22 Å atom -1 , and the difference in energy between the structures is ∆E = 205 meV atom -1 (evaluated at the B3LYP/STO-3G level). Although this is by no means a conclusive test of the reliability of the AM1* method for our given application, it nonetheless adds confidence to the validation work carried out previously for organometallic compounds [5,65]. Furthermore, since the CPU time required to carry out the SEMO calculation was a factor of approximately 10 3 lower than required to achieve the DFT result, the latter technique is still impractical for a systematic study such as undertaken here.…”

“…The AM1/d scheme has the advantage that results obtained for non-transition-metal atoms are identical to those for the original AM1 method, while the former is additionally able to reproduce chemical properties of complex organometallic and bioinorganic compounds of Mo with high precision [65]. The Mo parameters in AM1/d were later incorporated in a slightly modified form by the Clark group into their AM1* Hamiltonian [5,66], which uses a distance-dependent core-core repulsion for some interactions. The same group then later reported AM1* parameters for Al, Si, Ti and Zr [67].…”

“…Of course, only an exhaustive search would establish with certainty the global minimum structure, and this was not attempted here. Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 Deleted: Figure 4 ... [2] ... [1] ... [4] ... [14] ... [7] ... [5] ... [17] ... [3] ... [13] ... [18] ... [9] ... [19] ... [15] ... [16] ... [20] ... [6] ... [11] ... [21] ... [10] ... [12] ... [22] ... [8] …”

Specific Reaction Parametrization of the AM1/d Hamiltonian for Phosphoryl Transfer Reactions: H, O, and P Atoms

“…[84][85][86][87] In this section, the major differences of these models are outlined, and a description of the slightly modified AM1/d-PhoT model is provided.…”

Density-functional expansion methods: grand challenges

“…This is, in fact, what the polarizabilities ultimately are: measures of response due to distant electrostatic perturbations. In particular, the isotropic dipole polarizability of a molecule is α = (α xx + α yy + α zz )/3, where (17) and (18) and E x are the electric dipole moment and field strength in the x-direction, respectively. …”