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Eyringpy is a program for calculating thermochemical properties and rate constants for reactions in the gas phase and in solution. This code is written in Python and its most important features are a user-friendly interface and a simple input format. Unimolecular and bimolecular systems with one and two products are supported. Thermochemical properties are estimated through canonical ensemble and rate constants are computed according to the transition state theory. One-dimensional Wigner and Eckart tunneling corrections are also available. Rate constants of bimolecular reactions involving the formation of pre-reactive complexes are also estimated. Eyringpy introduces specific methods to correct rate constants for reactions in solution, the Collins-Kimball theory to include the diffusion-limit, the Marcus theory for electron transfer processes, and the molar fractions to account for the solvent pH effect. Eyringpy is compatible with Linux, MacOs and Windows.

Rate constants for the reaction CH4 + Cl· → CH3· + HCl, in the range 200-300 K: (a) without corrections, (b) including Wigner correction, (c) including Eckart correction, and (d) experimental values.

Influence of the pH on the rate constants for the reaction NH3 + OH· → NH2· + H2O calculated at 298.15 K, including the diffusion and Eckart tunneling effect corrections.

For further details about Eyringpy and its methods please see the paper:


E. Dzib, J. L Cabellos, F. Ortíz-Chi, S. Pan, A. Galano, G. Merino "Eyringpy: A Program for computing  Rate Constants in the Gas Phase and in Solution" Int. J. Quantum Chem. 2019, 119, e25686.     



Eyringpy 1.0 is available for downloading through the Merino Research Group at Cinvestav. To obtain a copy of Eyringpy you should fill out a form and send it to or Professor Gabriel Merino or Eugenia Dzib. Then you will receive an executable compatible with the operating system you need.


Please download the order form here



The Eyringpy user’s manual can be download here.



Please cite the next references:


E. Dzib, J. L Cabellos, F. Ortíz-Chi, S. Pan, A. Galano, G. Merino "Eyringpy: A Program for computing  Rate Constants in the Gas Phase and in Solution" Int. J. Quantum Chem2019, 119, e25686   


E. Dzib, J. L. Cabellos, F. Ortiz-Chi, S. Pan, G. Merino, Eyringpy 1.0, Cinvestav, Merida, Yucatan 2018.



For further information about Eyringpy, to report bugs and comments about the manual or the web page, please contact us via


Professor Gabriel Merino




M. Sc. Eugenia Dzib



Papers citing Eyringpy


18. Van Quan, V., Phu, H.T., Thao, P.T.T. and Nam, P.C. "Substituent effects on antioxidant activity of monosubstituted indole‐3‐carbinols: A DFT studyVJCH, 2019, 57, 728-734.


17. Machado, H. G.; Sanches-Neto, F. O.; Coutinho, N. D.; Mundim, K. C.; Palazzetti, F.; Carvalho-Silva, V. H. "“Transitivity”: A Code for Computing Kinetic and Related Parameters in Chemical Transformations and Transport Phenomena" Molecules, 2019, 24. Accepted.


16. Vo, Q. V.; Van Bay, M.; Nam, P. C.; Mechler, A. "Hydroxyl Radical Scavenging of Indole-3-Carbinol: A Mechanistic and Kinetic StudyACS Omega, 2019, 4, 19375–19381.


15. Vo, Q. V.; Van Gon, T.; Van Bay, M.; Mechler, A. "Antioxidant Activities of Monosubstituted Indolinonic Hydroxylamines: A Thermodynamic and Kinetic StudyJ. Phys. ChemB, 2019, 123, 10672–10679.


14. Ngo, T. C.; Nguyen, T. H.; Dao, D. Q. "Radical Scavenging Activity of Natural-Based Cassaine Diterpenoid Amides and AminesJ. Chem. Inf. Model2019, 59, 766–776.


13. Thong, N. M.; Vo, Q. V.; Huyen, T. L.; Van Bay, M.; Tuan, D.; Nam, P. C. "Theoretical Study for Exploring the Diglycoside Substituent Effect on the Antioxidative Capability of Isorhamnetin Extracted fromACS Omega, 2019, 4, 14996–15003.


12. Vo, Q. V.; Tam, N. M.; Van Bay, M.; Mechler, A. "The Radical Scavenging Activity of Natural Ramalin: A Mechanistic and Kinetic StudyChem. Phys., Lett. 2020, 739, 137004.


11. Vásquez-Espinal, A.; Yañez, O.; Osorio, E.; Areche, C.; García-Beltrán, O.; Ruiz, L. M.; Cassels, B. K.; Tiznado, W. "Theoretical Study of the Antioxidant Activity of Quercetin Oxidation ProductsFront Chem., 2019, 7, 818.


10. Vo, Q. V.; Nam, P. C.; Thong, N. M.; Trung, N. T.; Phan, C.-T. D.; Mechler, A. "Antioxidant Motifs in Flavonoids: O-H versus C-H Bond DissociationACS Omega, 2019, 4, 8935–8942.


9. Vo, Q. V.; Cam Nam, P.; Van Bay, M.; Minh Thong, N.; Hieu, L. T.; Mechler, A. "A Theoretical Study of the Radical Scavenging Activity of Natural StilbenesRSC Adv., 2019, 9, 42020–42028.


8. Vo, Q. V.; Mechler, A. "In Silico Study of the Radical Scavenging Activities of Natural Indole-3-CarbinolsJ. Chem. Inf. Model, 2019Accepted.

7. Q. V. Vo, M. V. Bay, P. C. Nam, and A. Mechler. "Is Indolinonic Hydroxylamine a Promising Artificial Antioxidant?" J. Phys. Chem., B, 2019, accepted.

6. S. Gómez and A. Restrepo. "Noble gas dimers confined inside C 70" Phys. Chem. Chem. Phys., 2019, 162, 318.

5. Q. V. Vo, P. C. Nam, N. M. Thong, N. T. Trung, C. T. D. Phan, and A. Mechler. "Antioxidant Motifs in Flavonoids: O–H versus C–H Bond DissociationACS Omega, 20194, 8935-8942.

4. G. Merino, A. Muñoz‐Castro, M. A. C. Nascimento, and A. Vela, "Theoretical chemistry in Latin America" Int. J. Quantum Chem.2019119, e25852.

3. W. Wei, J. Ma, D. Xie, and Y. Zhou. "Linking inhibitor motions to proteolytic stability of sunflower trypsin inhibitor-1", RSC Adv., 20199, 13776-13786.

2. T. C. Ngo, N. Thi Hau and D. Q. Dao. "Radical Scavenging Activity of Natural-based Cassaine Diterpenoid Amides and Amines" J. Chem. Inf. Model., 2019, 59, 766−776.

1. S. Llano, S. Gómez, J. Londono-Londono and A. Restrepo, "Antioxidant Activity in Curcuminoids" Phys. Chem. Chem. Phys., 2019, 21, 3752-3760.

Prof. Gabriel Merino

Departamento de Física Aplicada
Centro de Investigación y de Estudios Avanzados
Unidad Mérida
Km. 6 Antigua carretera a Progreso
Apdo. Postal 73, Cordemex, 97310, Mérida, Yuc., México

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Gabriel's Phone: (52) 999 942 94 00 Ext 2591
Lab's Phone:      (52) 999 942 94 00 Ext 2576


Twitter: @theochemmerida

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