Plotting molecular electrostatic potential surfaces (MEPS) with ORCA
Research note
The orca_vpot program calculates the electrostatic potential for a set of points provided by the user. But it can be boring or hard. here is how you can do it.
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Non-Interactive plotting using orca_plot
Research note
ORCA provides a convenient way to plot orbitals and densities in the form of a small binary called orca_plot. Here is how to use it more conveniently.
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How can Spin-Orbit-Coupling allow interactions between states with different multiplicities?
Research note
Here’s a longer sketch of what Paul’s comment is describing. In the absence of spin–orbit coupling (SOC), the available states have well-defined spin and orbital angular momentum components which can be separated.…
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Why is manganese(II) colored although the transition should be spin-forbidden?
Research note
Manganese oxidation states. Beakers with solutions of 0.00025M potassium permanganate(VII) (KMnO4, purple, left) and 0.25M manganese(II) sulfate (MnSO4, pale pink, right). Selection rules The intensity of the transition from a state to a state is governed by the transition dipole moment (strictly, it is proportional to ): (1) where is the usual…
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Dynamic versus static electronic correlation
Research note
In quantum chemistry, when a nomenclature in which one distinguishes between “static” and “dynamic” correlation is used, “correlation” referrers to all the deficiencies of the Hartree-Fock (HF) single-determinantal approach. For instance, the…
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The spin 1/2
Research note
Particles with spin 1/2, like the electron, must perform two 360° rotations to return to their initial state. This concept is hard to visualize but, basically, if we imagine the electron wavefunction…
