Utilize Orbital Overlap with Multiwfn

Using the overlap integral function in Multiwfn with some potential usages.

http://sobereva.com/163

In Gaussian

Prepare the Input for fragment(pop=full) and complex(pop=full IOp(3/33=1)). The files are same for CDA analysis, so it’s convenient to do both.

In Multiwfn

Input the complex and fragments:

[complex_path]
100
15
[frag1_path]
[frag2_path]
[Orbital_frag1_Index],[Orbital_frag2_Index]

This give the overlap integral(S) for multiplying wavefunction of Orbital_frag1 and Orbital_frag2

Potential usages

In competing TSs:

• Spatial overlap difference (e.g. steric effect)
  • Demo directly (e.g. steric effect and how it influence the electronic effect)
• Atomic coefficient difference
  • A validation
  • Utilize the $ \frac{S^2}{d\epsilon} $ to weight difference in different orbitals
• Overall Coefficient difference(Polarzation)
  • affect the positional overlap (without internal positional difference)
  • example: https://pubs.rsc.org/en/content/articlelanding/2020/sc/d0sc02901g#!divAbstract Above Fig. 2 in analysis.