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Chemical Reaction Transition State Calculation


Molecular conformational changes and chemical reactions frequently involve transition states, i.e., the movement of the process on the potential energy surface often goes through a point that satisfies the above conditions. It is significant to note that transition state structures are not always present in chemical reactions. It is challenging to obtain transition state structures experimentally since they only persist for relatively brief periods of time. Currently, the most effective tool for forecasting transition states is computational chemistry.

Alfa Chemistry is dedicated to providing chemical researchers with comprehensive and accurate transition state calculations for chemical reactions. We use molecular mechanics, quantum chemistry, and other methods to find the molecular structure of transition states theoretically.

Understanding Transition States

Nuclear configurations are changed from the reactant state to the product state during chemical reactions. There are numerous potential paths for converting reactants into products for polyatomic compounds. All paths are included in a comprehensive discussion of chemical reaction kinetics. A specific conformation along the reaction coordinate is the transition state of a chemical reaction in chemistry. The state with the maximum potential energy along that reaction coordinate is what is meant by this term. Activated complexes of a reaction can refer to the transition state or other states along the reaction coordinate between reactants and products, especially those close to the transition state.

Reaction energy diagram for 2BrNO 2NO + Br2.Fig 1. Reaction energy diagram for 2BrNO → 2NO + Br2. (Fieberg J. E, et al. 2012)

The transition state theory states that after reactants have passed through the configuration of the transition state, they invariably proceed to form products. Determining the transition state helps to understand the reaction mechanism, as well as calculating the reaction rate from the potential barrier height.

Our Services

Alfa Chemistry mainly uses quantum chemistry and molecular mechanics to calculate reaction transition states. Based on various well-designed calculation methods, we provide the following high-quality and fast services:

Project NameChemical Reaction Transition State Calculation Service
DeliverablesWe provide customers with transition state structural analysis results and all raw data.
Samples RequirementOur services require specific requirements from you.
Timeline DecideAccording to customers' needs
PricePlease contact us for an inquiry

Alfa Chemistry Calculation Methods

  • Quantum Chemical Transition State Calculation Method

a. Quasi-Newton Raphson (NR) Method
b. Gradient Extramal Method (GE2JJH Method, GE2SR Method)
c. Trust-Region Image Minimization (TRIM) Method
d. Image Potential in Trinsic Reaction Coordinate (IPIRC) Method
e. Constrained Optimization (CONOPT) Method
f. Line-Then-Olane (LTP) Method

  • Molecular Mechanics Calculation of Transition State Methods

a. Rigid Transition State Model
The outcomes of calculations in quantum chemistry are employed as a model in this approach. The model is initially placed in the study system so that the bonds involved in bond production and bond breaking stay unchanged from the quantum chemistry calculations, and the remainder of the system is molecularly optimized. The model transition state is then discovered using quantum chemistry. The borohydride reaction is among the best instances of this strategy in action.

b. Flexible Transition State Model
This method involves optimizing the transition state model discovered through quantum chemistry, which necessitates the creation of several molecular mechanics parameters. The use of this method is justified because numerous quantum chemical simulations demonstrate that the transition states of similar types of chemical processes have roughly the same structure.

c. Constructed Potential Function Method
This method involves large changes in reactants, products, transition states, and molecular configurations in the optimization process, so a set of parameters must be developed to accommodate a wide range of molecular changes.

Constructed Potential Function Method

Transition State structural calculations provide an effective way to optimize chemical processes. Our personalised full service will meet your innovative learning needs. If you are interested in our services, please feel free to contact us. We are happy to work with you and witness your success!


  • Fieberg J. E, et al. (2012). "Visualizing Reaction Progress and the Geometry and Instability of the Transition State." J. Chem. Educ. 89(9): 1174-1177.

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