I am working on the reaction on the surface of water ice using ab initio and density functional methods. Suppose If a molecule A is adsorbed on the surface of water ice and B react with that forming AB. How should i approach to calculate rate coefficient for A +B ==> AB.
For the gas phase reaction, I am using multiwell (
aoss.engin.umich.edu/multiwell/) program. is it a correct way to assume reactant A and ice as one molecule (while forming input to the multiwell program) and assuming B as second reactant. I do not have experimental data to verify my approach so please help me in this regard. A model of ice is attached. I am using Gaussian 09 for ab initio calculations.
There are testjobs here with detailed application to different problematics:
http://www.cup.uni-muenchen.de/ch/compchem/testindex.html
Hi,
You can check KiSThelP (http://kisthelp.univ-reims.fr/) which is a very easy to use Java based program for calculating rate constants from DFT results.
Thank You Turbasu Sengupta and Oleg B. Gadzhiev for your informative answer. I am working on them.
Keshav Singh.
From your question “is it a correct way to assume reactant A and ice as one molecule (while forming input to the multiwell program) and assuming B as second reactant”.
If you want to go by your above assumption which I do feel is not right, here is an approach to get vague/close results.
Multiwell program can solve Termolecular reactions. You simply use your ice vibrational frequency log files coupled with those of reactant A and B to generate your Multiwell input files. From your reaction (ice + A + BAB), a cluster (AB) is formed. You need to find the Termolecular recombination rate which you will need to calculate the final rate. Final rate= Termolecular recom.. rate * Population of AB
To get accurate results, you need to calculate the surface absorption energy of A on ice. You can use VASP to build layers of ice and molecule of A for the energy calculation. Gaussian should be able to calculate the vibrational frequencies of absorped A on solid ice for Multiwell input.
Cheers
- Badges
- Science topic
- Similar topics
- Methodology
- Research Methodology
- Research Papers