Firstly, I calculate the DFT optimization of the cis and trans isomers, separately, NOW, What should i do to predict the ratio or the more stable of cis/trans isomer ???
Using Gibbs free energy calculate the constants according to the equation dG=-RTlnK
You should also performed frequency calculation of both isomers and you will get details of thermochemistry. From these varios energy values i think you resolve your problem.
Its very easy. Calculate de frequencies, of both isomers, and them you will obtain the free gibbs energies values. Using the gibbs free energy values of both isomers you can calculate the delta G and by equation dG=-RTlnK calculate the equilibrium constant and the rate of the isomers.
You can calculate three parameters by which you evaluate which of the compoundd are more stable and which is the more ratio.
Heat of formation
Binding energy
HOMO-LUMO energy gap
These parameters you can calculate it after geometry optimization for cis and trans isomers
You can do this by performing the geometry optimization of each isomer separately in order to know the energy level of it and this process is done through draw the cis and trans compound .
Heat of formation can be obtained by atomization or isodesmic methods but isodesmic reaction method is better than atomization.Binding energy for each of cis and trans isomers are calculated by binding energy formula and the parameter involved in BE equation can be obtained from thermochemistry part of frequency calculations.
- Badges
- Science topic
- Similar topics
- Engineering
- Chemical Engineering