Margarita Mayoral Villa
Dec. 2008
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Examine the properties of the metal-ligand
bond in the scorpionate compounds.
Examine the variations that could be possible if
the metal ion changes its oxidation state.
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Explains how the electrons have both particleslike and waves-like behaviour.
Use the Schrödinger equation to obtain the
energy and other characteristics of the atoms or
molecules.
Where:
Or in a Hamiltonian form:
Where:
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Hartree-Fock Method (ab initio)
Semiempirical Methods
Density Functional Methods (FDT)
1) Stationary wave function
2)Born -Oppenheimer approximation:
Electronic wave function in a static nuclei field.
Where:
Is the electronic Hamiltonian
Is the electronic wave function
Is the effective nuclear potential function
3) Linear combination of atomic orbitals (LCAO)
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Is the base of all other methods.
It`s applied in atoms with many electrons,
molecules and solids.
It solve the Schrödinger equation using a linear
combination of atomic orbitals (LCAO) like the
wave function.
It is an iterative method.
When the method finds the minimal energy then
that wave function is considered like the correct
one, and then the observables are calculated.
Use parameters derived of experimental data to
simplify the approximation to the Schrödinger
equation.
 Relatively inexpensive.
Appropriated for:
 Very large systems.
 As a first step in a very large systems.
 For ground state molecular systems for which the
semi-empirical method is well-parametrized and
well-calibrated.
 To obtain qualitative information.
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Derived from the Thomas-Fermi-Dirac model (1920`s).
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Slater`s fundamental work (1950`s).
Models electron correlation via functionals of the electron density.
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Hohenberg-Kohn theorem (1964).
Demonstrated the existence of a unique functional which determines
the ground state energy and density exactly.
Kohn and Sham propound the approximate functionals employed
currently by DFT methods:
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Where:
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Geometry
Homo –Lumo properties
Frequencies
Spectra
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All the calculations were performed in the
Gaussian 03 program.
We use Gauss View for develop the ligands and
for visualize the results.
The Hartree – Fock method doesn`t works well
with the geometry optimizations.
Then all the calculations were made with Density
Functional Theory.
We do first the calculations for the ligand:
Charge: 0
Multiplicity: 1
And in the second step we do the calculations for:
Charge: +1
Multiplicity: 2
Then we can do the comparisons between the results of both ligands.
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The better theoretical method in this work is the DFT method
using the hibrid exchange-correlation functional: B3LYP, (Becke`s
three-parameter formulation) with the 6-31G(d) basis set.
The computational cost for this method is acceptable.
The comparison between the geometries obtained from the
calculations with the experimental are very closely.
At the moment, the geometry obtained for charge +1 is very alike
to that obtained for charge 0.
We must to compare the spectrum UV-visible obtained from the
calculations with that obtained experimentally to be sure that the
calculations goes well.
At the moment we can see that the electronic distribution is over
the central metal atom in the case of charge 0, and for charge +1
we can see that this is distribuited over the central atom in the case
of the HOMO alpha, but for the HOMO beta, this charge seems to
go out of the center.
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We must to calculate the Spectrum UV-Vis of
the molecule with charge 0 to compare with the
experimental Spectrum.
We have to start with the geometry
optimization of the Tp ligand, using the same
method and compare with the experimental
one.
Then, confirm the stability, calculate HomoLumo, frequencies, spectrum UV-Vis.
Do the same with the charge +1.