Dear all,
We have used OpenMolcas to compute the MECP and MECI points, and verified the reactant and product structures using MEP and LIIC methods. We are interested in investigating the branching ratios of multiple reaction pathways that pass through these points. However, we have not used MESMER or performed calculations related to branching ratios before.
We would like to ask for your guidance on how to carry out such calculations. We noticed that in the MESMER examples, there are two files in the spin_forbidden_kinetics section—WKB_test.xml and ZNtest.xml—which seem to involve MECP pathways. Would it be feasible to use MESMER to calculate the branching ratios among different pathways, such as those involving MECP, MECI, direct dissociation, and transition state mechanisms?
Any help or advice you could provide would be greatly appreciated. Thank you very much for your support!
Best regards,
Rui.
Last edit: liurui 2025-04-26
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We have used OpenMolcas to compute the MECP and MECI points, and verified the reactant and product structures using MEP and LIIC methods. We are interested in investigating the branching ratios of multiple reaction pathways that pass through these points. However, we have not used MESMER or performed calculations related to branching ratios before.
We would like to ask for your guidance on how to carry out such calculations. We noticed that in the MESMER examples, there are two files in the spin_forbidden_kinetics section—WKB_test.xml and ZNtest.xml—which seem to involve MECP pathways. Would it be feasible to use MESMER to calculate the branching ratios among different pathways, such as those involving MECP, MECI, direct dissociation, and transition state mechanisms?
Any help or advice you could provide would be greatly appreciated. Thank you very much for your support!
There are three methods available in MESMER aimed at spin forbidden kinetics, the WKB and Zhu-Nakamura methods you mention above and the Landau-Zener method. All these methods are documented in the manual. I have to say that I did not implement these methods myself so I only have an approximate idea as to how they work, but in principle I believe that they can essentially be substituted for an RRKM term. Without knowing the details of your system, it is hard for me to comment on branching ratios but as we calculate branching ratios for other systems I cannot see an obvious problem. The main difficulty is usually obtaining the parameters for the spin forbidden transition but it seems you have these already.
Please do not hesitate contacting me again if you think I can help.
With regards, Struan
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Dear all,
We have used OpenMolcas to compute the MECP and MECI points, and verified the reactant and product structures using MEP and LIIC methods. We are interested in investigating the branching ratios of multiple reaction pathways that pass through these points. However, we have not used MESMER or performed calculations related to branching ratios before.
We would like to ask for your guidance on how to carry out such calculations. We noticed that in the MESMER examples, there are two files in the spin_forbidden_kinetics section—WKB_test.xml and ZNtest.xml—which seem to involve MECP pathways. Would it be feasible to use MESMER to calculate the branching ratios among different pathways, such as those involving MECP, MECI, direct dissociation, and transition state mechanisms?
Any help or advice you could provide would be greatly appreciated. Thank you very much for your support!
Best regards,
Rui.
Last edit: liurui 2025-04-26
Dear Rui,
First, my apologies for this slow response.
There are three methods available in MESMER aimed at spin forbidden kinetics, the WKB and Zhu-Nakamura methods you mention above and the Landau-Zener method. All these methods are documented in the manual. I have to say that I did not implement these methods myself so I only have an approximate idea as to how they work, but in principle I believe that they can essentially be substituted for an RRKM term. Without knowing the details of your system, it is hard for me to comment on branching ratios but as we calculate branching ratios for other systems I cannot see an obvious problem. The main difficulty is usually obtaining the parameters for the spin forbidden transition but it seems you have these already.
Please do not hesitate contacting me again if you think I can help.
With regards, Struan