New answers tagged theoretical-chemistry
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If you regard chemistry as the science about the (chemical) interconversion of matter, then the basic principle ruling it is Le Chatelier´s.
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(https://i.stack.imgur.com/znrms.jpg)
we cannot determine the extent of s p and d character in hybrid orbitals.
but we can say that s character is greater in axial positions as angle is more than in equatorial positions.
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Chemistry is different from physics in that it's focus has historically been on understanding what gives rise to the variation of matter, rather than asking "what is matter", which is one of the more profound questions physics asks. By extension chemistry also concerns itself with how matter can be transformed within this manifold of possible forms. As such, ...
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This is an inherently subjective question. It's very difficult to come up with an answer that isn't just a fundamental principle of physics. My personal opinion is the following:
Chemistry is the study of interacting electrons.
Now, obviously the electrons are only near enough to interact because the positive charges of nuclei don't let the electrons fly ...
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Chemistry seeks to describe, among other things, chemical changes in the world. All spontaneous changes obey a law, and that is that they increase the entropy of the universe. Hence, a fundamental principle of chemistry could arguably be:
dS > 0
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The fundamental principle of chemistry is probably the conservation laws : energy and matter. Maybe also the universal attraction between positive and negative charges and the repulsion between similar charges. These laws have no exceptions, as far as I know.
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I agree in part with Mithoron and MaxW's comments: these are different molecules, not even sharing a mutual atom (e.g. C-O vs C-C), so direct comparison is restricted.
However, Pauling's concept of electronegativity does explain why, in general, the heteronuclear A-B bond is stronger than the average of the homonuclear A-A and B-B bonds. the difference in ...
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(1) Is this all correct so far?
Yep.
(2) If so, is it justified to use it in numerical derivations as an
eigenfunction of the Hamiltonian, i.e. can we write
$\hat{H}\ket\Phi\overset{?}{=}E_{0}\ket\Phi$ or are we restricted to
$\bra\Phi\hat{H}\ket\Phi=E_{0}$?
...
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It's an older question, but one worth answering!
For the uninitiated, second quantization is a bookkeeping technique that describes many-particle systems as excited states of a field, usually taken to be the ...
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Let us begin with the following principle: the CC ansatz always returns an appropriate electronic wavefunction (meaning a combination of Slater determinants). Still, at least in a non-relativistic approach, the Hamiltonian does commute with the Spin operator
\begin{equation}
S^{2}=S_{+}S_{-}-S_{z}+S_{z}^{2}
\end{equation}
(I'm using atomic units here)
and ...
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