Erying Equation and Enthalpy of Activation

[Sulstice]

Hi,

Forgive me if this is elementary. I want to compute reaction rates between an open and closed ring in a molecule.

If we take a z-matrix of the input and output

And pass it through the psi4 code:

import psi4 

psi4.set_options({
  'scf_type': 'df',
  'g_convergence': 'gau_tight',
  'freeze_core': 'true',
})

zmatrix =  ''

molecule = psi4.geometry(zmatrix)
molecule.update_geometry()

energy, wave_function = psi4.energy(
           'mp2/cc-pvqz',
            return_wfn=True,
            molecule=molecule
 )

frequency = psi4.frequencies(
      ' mp2/cc-pvqz',
       ref_gradient=wave_function.gradient(),
       molecule=molecule
)

I can run the thermo package and obtain energies in both closed/open states but I was wondering how, thermodynamically (the different energetic terms: Thermal Energy, Enthalpy, Gibbs Free Energy), this relates to the erying equation.

Is the enthalpy of activation = enthalpy of closed - enthalpy of open.

[TiborGY]

This question would probably be better asked on the Matter Modeling sackexchange site, or maybe the Psi4 forum. But not as a Github issue.

Make sure you are accounting for the fact that your cyclic molecule has 4 fewer hydrogen atoms! If you want to compute any kind of energy difference between those two molecules, those hydrogens need to go somewhere, your reaction needs to be balanced.

[JonathonMisiewicz]

Unless there's a question about Psi4 specifically, I'm going to close this shortly. Tibor is quite correct that this is better as a stack exchange question.