ChemRate CPS, allows the calculation of a Arrhenuis factor and a rate constant of chemical reactions with split-hair accuracy, precision of calculation frequently above precision of the observational measurings. Evaluations bases on modern quantum chemistry methods and the unique algorithms allowing considerably to increase precision of calculation.

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Сhemical kinetics, investigates reaction rate. Fundamental law of a chemical kinetics is the postulate expressing dependence of reaction rate from concentration of reactants: reaction rate in each instant is proportional to product of concentrations of the reactants raised in some degree. So, for reaction can be noted:

- rate constant, - concentration of carbonic oxide, - concentration of water

rate constant, can be found from the Arrhenius equation:

Ea - Energy of activation, A - Arrhenius factor

Arhenuis factor can be determined from the next equation:

Qtrans - tranclational partition function, Qrot - rotational partition function, Qvib - vibrational partition function, Qint.rot - partition function for internal rotations. Q#-partition functions for transition state

Translational partition function:

Rotational partition function:

Ia, Ib, Ic - moments of inertia of a molecule concerning main spin axes, - symmetry number, quantity of times a molecule can be combined at rotational displacement

Vibrational partition function for a polyatomic molecule with number i vibrational degrees of freedom can be written down in the form of product of the partition functions i various oscillators:

Internal rotation

For qualitative calculation of a preexponential factor, it is necessary to consider an internal rotation. Internal rotation can be free, hindered and at a large barrier becomes torsion vibrations. The shape of function of a potential of rotation determines symmetry of a top or absence of symmetry. Potential of the symmetric top is featured by the equation:

Vo - height of a barrier, n - symmetry number of a top

The potential of rotation of the asymmetrical top, can be presented in the form of a Fourier series:

:

n - number in decomposition of potential function

Energy (eigenvalues) of internal rotation is the solution of the quantum mechanical equation:

Using eigenvalues of energy of an internal rotation, we can take advantage of the reference formula for partition function: