Chemistry Reference
In-Depth Information
realises that atomic nuclei are heavier than electrons, and hence have an equation of
motion that is to a significant degree separable from the motion of the electrons.
From the viewpoint of
quantum mechanics this makes no difference -
all particles form part of the system which must be treated quantum mechanically.
The remainder of the structures, E and B are more specifications of the remain-
der of the system in the language of simple quantum mechanics - one specifying
that the electrons will be treated with the machinery of quantum mechanics, the
other specifying the basis in which the quantum mechanical wavefunction will be
expanded - they are not overly interesting from a conceptual space point of view.
The links, which I present in detail in Hettema (
2012a
), express the necessary
relationships in relatively complex looking set-theoretic language. The conceptual
spaces approach, which I have utilised here, allows for a more intuitive, non-formal
characterisation of the same issues.
Eyring
principled
'
'
quantum chemistry adds further revisions
onto ab initio quantum chemistry by specifying a distinction between
s notion of
semi-empirical
'
'
'
core
and
'
'
electrons which is unprincipled from the viewpoint of ab initio quantum
mechanics, but necessary from the viewpoint of practically implementing the
theory without the help of a computer.
valence
'
'
2. The connection between statistical mechanics and transition state theory ismade by
eliminating, from the partition function of the activated complex, the translational
component due to the motion along the reaction coordinate (see (Glasstone
et al.
1941
,p.189)).
15
This step, however, is captured through the addition of a
'
special
law
on statistical mechanics, and moreover,
this
special
law
'
'
'
characterises the
'
transition state
'
precisely in terms of its degrees of freedom.
Through this specification, the notion of
'
transition state
'
, the
'
saddle
'
point on
the reactive potential energy surface, can be specified as a
'
special law
'
on top of
'
ab initio
'
quantum chemistry.
3. The comparisons between the thermodynamic, collision and
theories
are at this stage difficult to determine, since detailed structuralist character-
isations of these theories are not readily available. However, one would expect
that these characterisations will yield similar insights.
'
absolute
'
2.4.3 Reduction Postulates and Belief Revision
The characterisations in terms of
can be seen, in the traditional
theory of reduction, as reduction postulates which tie the formal paraphrases of the
reduced and reducing theory to each other. In particular, the analysis in terms of
conceptual spaces allows for a precise characterisation of some of the terminology
conceptual spaces
'
'
15
A detailed discussion of why this is so falls outside the scope of this paper, but can easily be
determined by stepping through the mathematics.
