AIMPs

Aminotri(methylenephosphonic acid) [ATMP or AMP] is the least expensive phosphonate. It is a good, general-purpose, cost-effective scale inhibitor an effective chelant and the most thermally stable of all the common phosphonates. It is satisfactory up to at least 700 psia. However, if fed as a concentrate AIMP may easily form insoluble calcium phosphonate and it may also affect copper. ATMP has a sequestration value of 870 mg CaC03/g product at a pH level of 11 and for iron, a sequestration value of 150 mg Fe/g product at a pH level of 10. The pentasodium salt has a MW of 409. Examples include Dequest 2000/2006, Mayoquest 1230, Phos -2, Briquest 301-50A, Unihib 305, and Codex 8503. 

Figure4.7 Relativistic bond contractions A re for Au2 calculated in the years from 1989 to 2001 using different quantum chemical methods. Electron correlation effects Acte = te(corn) — /"e(HF) at the relativistic level are shown on the right hand side of each bar if available. From the left to the right in chronological order Hartree-Fock-Slater results from Ziegler et al. [147] AIMP coupled pair functional results from Stbmberg and Wahlgren [148] EC-ARPP results from Schwerdtfeger [5] EDA results from Haberlen and Rdsch [149] Dirac-Fock-Slater...

If the number density of adatoms is not too large and the applied field is in the field electron emission range, one can show that, in general, Aimp < [Pg.269]

Since in current molecular modeling tasks the Gaussian orbitals or their linear combinations are used, one can guess that they provide the explicit form of the core states. Inserting the Gaussians in the expressions for the Coulomb and exchange superoperators yields numerous approximate forms of the pseudopotentials, which can be exemplified by the formulae employed in the ab initio model potential (AIMP) [36] ... 

The most common quantum chemical programs—Gaussian (8), GAMESS (9), Turbomole (10), CADPAC (11), ACES II (12), MOLPRO (13), MOLCAS (14), and the newly developed TITAN (15)—are able to run pseudopotential calculations. Please note that CADPAC and MOLCAS can only use so-called ab initio model potentials (AIMPs) in pseudopotential calculations. Such AIMP differ from ECPs in the way that the valence orbitals of the former retain the correct nodal structure, while the lowest-lying valence orbital of an ECP is a nodeless function. Experience has shown that AIMPs do not give better results than ECPs, although the latter do not have the correct nodal behavior of the valence orbitals... 

The AIMP method in its present form starts from a quasirelativistic all-electron Hartree-Fock calculation for the atom under consideration in a suitable electronic state and approximates the operators on the left-hand side of Equation (3.10) for an atomic core X as described in the following. 

In the calculations based on effective potentials the core electrons are replaced by an effective potential that is fitted to the solution of atomic relativistic calculations and only valence electrons are explicitly handled in the quantum chemical calculation. This approach is in line with the chemist s view that mainly valence electrons of an element determine its chemical behaviour. Several libraries of relativistic Effective Core Potentials (ECP) using the frozen-core approximation with associated optimised valence basis sets are available nowadays to perform efficient electronic structure calculations on large molecular systems. Among them the pseudo-potential methods [13-20] handling valence node less pseudo-orbitals and the model potentials such as AIMP (ab initio Model Potential) [21-24] dealing with node-showing valence orbitals are very popular for transition metal calculations. This economical method is very efficient for the study of electronic spectroscopy in transition metal complexes [25, 26], especially in third-row transition metal complexes. 

---