Reaction kinetics selection
Select the Reaction kinetics option on the CASTEP Analysis dialog to display the Reaction kinetics dialog.
Results file: Indicates the document containing the reaction ingredients. This field displays the name of the active document. You can change the active document by clicking on the desired document window or by double-clicking on the document name in the Project Explorer.
Reaction kinetics calculation can be performed only if the collection document contains well-defined reaction ingredients: the reactant(s), the product(s), and the transition state. All the structures must have Hessians and total energy calculated. Reactant(s) and product(s) systems must be in the ground state - that is all the eigenfrequencies must be real and non-negative.The transition state must be a valid saddle point with one and only one imaginary frequency for which eigenvectors represent the reaction path.
From: To: Specify the temperature range for the output of the calculated rate coefficient.
Apply tunneling correction: When checked, indicates that the reaction rate coefficient will be calculated taking into account the tunneling correction.
Threshold correction: Specify the value to be added to the DFT reaction threshold. This correction compensates for the underestimation of reaction barriers at the DFT level of theory.
Vibrational frequencies scaling: Specify the value of the scaling coefficient to be applied to calculated vibrational frequencies before evaluation of vibrational partition functions.
In some reactions, the transition state may have optical isomers with degeneracy n. These require the prefactor of the Arrhenius rate to be corrected by a factor n. Materials Studio does not automatically include this prefactor, users are encouraged to add it to the results study table by hand.
Calculate: Calculate and display a study table containing rate coefficients for the forward and reverse reactions.
The prefactor for the modified Arrhenius equation is calculated using T0= 298.15 K as reference temperature.
Access methods
| Menu | Modules | CASTEP | Analysis | Reaction kinetics |
| Toolbar |
 | Analysis | Reaction kinetics
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See Also:
CASTEP Analysis dialog
Calculating reaction kinetics
Project Explorer