Effective core potentials calculations

Gropen,0., Wahlgren,U. and Pettersson,L.G.M. (1982), Effective core potential calculations on small molecules containing transition metal ions , Chem.Phys. 66, 459... 

CEP-4G H to Rn Stevens, Basch and Krauss (1984) Used for ECP (effective core potential) calculations... 

Quantum chemical calculations on RE + /3-diketonate complexes are presently restricted to two approaches the effective core potential (ECP) and the SMLC/AMl method. The SMLC/AMl method is a very powerful addition to the semi-empirical molecular orbital method AMI in that it allows the prediction of geometric parameters of rare-earth /3-diketonate complexes of very difficult experimental determination. In this method the RE3+ ion is a sparkle represented by a -i-3e charge in the center of a repulsive spherical potential of the form exp(—ar). Recently, ab initio effective core potential calculations have also succeeded in reproducing the coordination polyhedron geometries of RE + /S-diketonate complexes with high accuracy . 

General Atomic and Molecular Electronic Structure System. Ab initio calculations with analytic energies and first derivatives and numerical second derivatives for effective core potential calculations. Parallel execution on UNIX workstations. VAX, IBM, Cray, HP, and UNIX workstations. 

The most extensive (relativistic) effective core potential calculations have recently been reported by Hay and Martin . Their best (CI(SD)) results are... 

Rappe, Smedley and Goddard (1981) Stevens, Basch and Krauss (1984) Used for ECP (effective core potential) calculations Dunning s correlation consistent basis sets (double, triple, quadruple, quintuple and sextuple zeta respectively). Used for correlation calculations Woon and Dunning (1993)... 

Two-component Relativistic Effective Core Potential Calculations for Molecules... 

The AIMP method as a common strategy for effective core potential calculations in molecules and for embedded cluster calculations, has been detailed and reviewed [17]. In this paper, we will pay special attention to its applications in the field of structure and spectroscopy of crystal defects created by actinide element impurities, where relativistic effects are a determinant factor, electron correlation and host embedding effects are also key elements, and not only the ground state but also large manifolds of hundreds of excited states are involved in the chemical and physical processes of interest. 

Fig. 8.3 Topology of the 2s2p overlap density of Be in the (a) all-electron and (b) effective core potential calculations (Reproduced from Ref. [26] with kind permission of Springer)...

Pettersson LG, Wahlgren U, Gropen O (1983) Effective core potential calculations using frozen orbitals applications to transition metals. Chem Phys 80 7-16... 

O. Gropen, U. Walgren, and L. Pettersson, Ghent. Phys., 66, 459 (1982). Effective Core Potential Calculations on Small Molecules Containing Transition Metal Atoms. 

Lee, Y.S. Two-component relativistic effective core potential calculations for molecules. In Schwerdtfeger, P. (ed.) Relativistic Electronic Structure Theory, Part n, pp. 352-416. 

Rykova, E.A., Zeitsevskii, A., Mosyagin, N.S., Isaev, T.A., Titov, A.V. Relativistic effective core potential calculations of Hg and eka-Hg (El 12) interactions with gold spin-orbit density functional theory modelling of Hg-Au and El 12-Au systems. J. Chem. Phys. 125, 241102(3) (2006)... 

Reduction of [Re(=0)I(RCCR)2l (R = Me, Et, Ph) with sodium naphthalenide afforded the unusual oxo species [Re(=0)(RCCR)2] Na, structurally characterised for R = Me and Ph. The allcyne ligands were observed to lie in a plane roughly perpendicular to the Re-O bond, but the CsC vectors were splayed rather than parallel. The structures have been rationalised using effective core potential calculations. 

The most common way of including relativistic effects in a calculation is by using relativisticly parameterized effective core potentials (RECP). These core potentials are included in the calculation as an additional term in the Hamiltonian. Core potentials must be used with the valence basis set that was created for use with that particular core potential. Core potentials are created by htting a potential function to the electron density distribution from an accurate relativistic calculation for the atom. A calculation using core potentials does not have any relativistic terms, but the effect of relativity on the core electrons is included. 

Relativistic effects are significant for the heavier metals. The method of choice is nearly always relativistically derived effective core potentials. Explicit spin-orbit terms can be included in ah initio calculations, but are seldom used because of the amount of computational effort necessary. Relativistic calculations are discussed in greater detail in Chapter 33. 

Effective core potentials (ECP) replace the atomic core electrons in valence-only ab initio calculations, and they are often used when dealing with compounds containing elements from the second row of the periodic table and above. 

Hay, P. J. Wadt, W. R. Ah initio effective core potentials for molecular calculations. Potentials for the transition metal atoms Sc to Hg. J. Chem. Phys. 1985, 82, 270-283. 

The twin facts that heavy-atom compounds like BaF, T1F, and YbF contain many electrons and that the behavior of these electrons must be treated relati-vistically introduce severe impediments to theoretical treatments, that is, to the inclusion of sufficient electron correlation in this kind of molecule. Due to this computational complexity, calculations of P,T-odd interaction constants have been carried out with relativistic matching of nonrelativistic wavefunctions (approximate relativistic spinors) [42], relativistic effective core potentials (RECP) [43, 34], or at the all-electron Dirac-Fock (DF) level [35, 44]. For example, the first calculation of P,T-odd interactions in T1F was carried out in 1980 by Hinds and Sandars [42] using approximate relativistic wavefunctions generated from nonrelativistic single particle orbitals. 

Generalized relativstic effective core potentials (GRECP), ab initio calculations, P,T-odd interactions, 253-259 Gene transcription, multiparticle collisions, reactive dynamics, 108-111 Geometric transition state theory, 195-201 Gillespie s algorithm, multiparticle collisions, reactive dynamics, 109-111 Golden Rule approximation, two-pathway... 

Relativstic effective core potentials (RECP), ab initio calculations, 253... 

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