A Toy Model of Chemical Reaction Networks - TBI - Universität Wien
A Toy Model of Chemical Reaction Networks - TBI - Universität Wien
A Toy Model of Chemical Reaction Networks - TBI - Universität Wien
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14 CHAPTER 3. MOLECULES<br />
Schrödinger equation<br />
ĤΨ = EΨ<br />
⇑<br />
⇓<br />
Born-Oppenheimer<br />
LCAO and Extended Hückel<br />
VSEPR and Tight Binding<br />
Generalized Eigenvalue Problem<br />
⎛<br />
⎞ ⎛<br />
⎞<br />
. .. . ..<br />
⎜<br />
⎟ ⎜<br />
⎟<br />
⎝ H AOi −AO j ⎠C = ⎝ S AOi −AO j ⎠CE<br />
. .. . ..<br />
Figure 3.1: Schematic derivation <strong>of</strong> the used electronic calculation method.<br />
H AOi −AO i<br />
, S AOi −AO j<br />
and K are given parameters (see equations 3.13).<br />
the Schrödinger equation is separated into a part describing the electronic<br />
wave function Ψ el for fixed nuclei,<br />
Ĥ el Ψ el = E el Ψ el , (3.3)<br />
and a part describing the nuclear wave function. The electronic Hamilton<br />
operator is:<br />
(<br />
)<br />
∑e −<br />
Ĥ el = − 1 2 ˆ∇<br />
∑nuc<br />
2 Z I<br />
∑e − ∑e − 1 ∑nuc<br />
∑nuc<br />
Z I Z J<br />
i −<br />
+ , (3.4)<br />
r<br />
i<br />
I iI r<br />
i j>i ij r<br />
} {{ } }{{} I J>I IJ<br />
} {{ }<br />
ĝ ij V n<br />
ĥ i<br />
+<br />
where ˆ∇ is the nabla operator, Z i is the nuclear charge <strong>of</strong> the atom i and r ij