# rmgpy.kinetics.Arrhenius¶

class rmgpy.kinetics.Arrhenius(A=None, n=0.0, Ea=None, T0=(1.0, 'K'), Tmin=None, Tmax=None, Pmin=None, Pmax=None, comment='')

A kinetics model based on the (modified) Arrhenius equation. The attributes are:

Attribute Description
A The preexponential factor
T0 The reference temperature
n The temperature exponent
Ea The activation energy
Tmin The minimum temperature at which the model is valid, or zero if unknown or undefined
Tmax The maximum temperature at which the model is valid, or zero if unknown or undefined
Pmin The minimum pressure at which the model is valid, or zero if unknown or undefined
Pmax The maximum pressure at which the model is valid, or zero if unknown or undefined
comment Information about the model (e.g. its source)

The Arrhenius equation, given below, accurately reproduces the kinetics of many reaction families:

$k(T) = A \left( \frac{T}{T_0} \right)^n \exp \left( -\frac{E_\mathrm{a}}{RT} \right)$

Above, $$A$$ is the preexponential factor, $$T_0$$ is the reference temperature, $$n$$ is the temperature exponent, and $$E_\mathrm{a}$$ is the activation energy.

A

The preexponential factor.

Ea

The activation energy.

Pmax

The maximum pressure at which the model is valid, or None if not defined.

Pmin

The minimum pressure at which the model is valid, or None if not defined.

T0

The reference temperature.

Tmax

The maximum temperature at which the model is valid, or None if not defined.

Tmin

The minimum temperature at which the model is valid, or None if not defined.

changeRate(self, double factor)

Changes A factor in Arrhenius expression by multiplying it by a factor.

changeT0(self, double T0)

Changes the reference temperature used in the exponent to T0 in K, and adjusts the preexponential factor accordingly.

comment

comment – str

discrepancy(self, KineticsModel otherKinetics) → double

Returns some measure of the discrepancy based on two different reaction models.

fitToData(self, ndarray Tlist, ndarray klist, str kunits, double T0=1, ndarray weights=None, bool threeParams=True)

Fit the Arrhenius parameters to a set of rate coefficient data klist in units of kunits corresponding to a set of temperatures Tlist in K. A linear least-squares fit is used, which guarantees that the resulting parameters provide the best possible approximation to the data.

getRateCoefficient(self, double T, double P=0.0) → double

Return the rate coefficient in the appropriate combination of m^3, mol, and s at temperature T in K.

isIdenticalTo(self, KineticsModel otherKinetics) → bool

Returns True if kinetics matches that of another kinetics model. Must match temperature and pressure range of kinetics model, as well as parameters: A, n, Ea, T0. (Shouldn’t have pressure range if it’s Arrhenius.) Otherwise returns False.

isPressureDependent(self) → bool

Return False since, by default, all objects derived from KineticsModel represent pressure-independent kinetics.

isSimilarTo(self, KineticsModel otherKinetics) → bool

Returns True if rates of reaction at temperatures 500,1000,1500,2000 K and 1 and 10 bar are within +/ .5 for log(k), in other words, within a factor of 3.

isTemperatureValid(self, double T) → bool

Return True if the temperature T in K is within the valid temperature range of the kinetic data, or False if not. If the minimum and maximum temperature are not defined, True is returned.

n

The temperature exponent.

setCanteraKinetics(self, ctReaction, speciesList)

Passes in a cantera ElementaryReaction() object and sets its rate to a Cantera Arrhenius() object.

toArrheniusEP(self, double alpha=0.0, double dHrxn=0.0) → ArrheniusEP

Converts an Arrhenius object to ArrheniusEP

If setting alpha, you need to also input dHrxn, which must be given in J/mol (and vise versa).

toCanteraKinetics(self)

Converts the Arrhenius object to a cantera Arrhenius object

Arrhenius(A,b,E) where A is in units of m^3/kmol/s, b is dimensionless, and E is in J/kmol

toHTML(self)

Return an HTML rendering.