default molecule property
For some molecule properties
which have multiplicity (e.g., names) one is considered by the
system to be the default. Note the default is user-selectable.
equilibrium product set
The set of all molecules that
are allowed to form in an equilibrium calculation.
fundamental property
(of a molecule) These are properties any of which will differentiate
two molecules.
group
A polyvalent atom (ligancy >=2) in a molecule, together with all its ligands
(Benson, 1976).
mechanism
a set of rate parameters and a specified thermset.
molecule
A chemical species defined by its fundamental
properties and including other properties and references. See the
Molecule property data format table.
molecule set
A collection of molecules.
molecular weight
Molecular weight of a molecule is
always calculated from the user-supplied atomic weights unless the
natural abundance flag is set, in which case the atomic weights in
the database are used.
natural abundance flag
A flag on a molecule indicating that all the atomic weights of the molecule
are assumed to be given by natural abundance. See molecular weight.
pressure-dependent or "third body" reactions
Reactions
for which the rate constant depends explicitly on the pressure or
equivalently the concentration of "M", the "third
body". Unimolecular decomposition reactions of this type are often
called "fall-off" reactions. Bimolecular reactions of this type are
often called "chemically activated". See www.ReactionXML.org for a
complete description of the types of pressure-dependent reaction
models handled in the OpenChem Workbench.
primary name
(of a molecule) See specifier.
project
A project consists of a collection of
user-defined groups of streams, a collection of user-defined
groups of runs, and some annotations.
pseudo-frequency cp fit
A thermodynamic fit of gas phase
heat capacity for a molecule, assuming that translational and
external rotation modes are fully activated. The vibrational modes
are approximated by three frequencies, and three mode degeneracies.
rate constant
A parameter that, when multiplied by the
driving force, determines the rate of disappearance of the
reactants. The rate constant is a function of temperature and
(sometimes) pressure. The functional form is usually modified
Arrhenius (k = A T^n exp(-Ea/RT)), however more complicated
expressions are used for pressure-dependent reactions (see www.ReactionXML.org for
details). The driving force is typically the product of the reactant
concentrations raised to the power of their stoichiometric
coefficients.
ratio of reaction rate constants
The average of the
ratios of reaction rates calculated from two different rate
constants at three temperatures. If a ratio is less than unity, it
is defined as the reciprocal of itself. So, a ratio of reaction rate
constants will be always larger or equal to unity. The temperatures
are starting temperature, ending temperature and middle temperature
of the overlap of the valid temperature range of the two reaction
rate constants.
reaction
Defined by a group of reactant molecules, a
group of product molecules, and their respective stoichiometric
coefficients. Often expressed in the form:
aA + bB + ... <-> qQ + rR + ...
The reaction is typically stoichiometrically balanced, but in special cases, unbalanced reactions will be allowed if the "balanced" stoichiometric flag is set to false (e.g., MW growth reactions where tracking hydrogen is not useful or desired).
reaction rate
An equation describing the rate at which a
chemical reaction occurs in units of mol vol^-1 time^-1.
reaction set
A collection of reactions.
reverse rate constant
Rate constant describing the rate at which products form reactants.
stream
A combination of temperature, pressure, flow rate, and molar composition of
molecular species present.
specifier
For a molecule, a unique name for the molecule in the database.
thermfit
A polynomial thermodynamic fit; i.e.,
thermodynamic data for a molecule. A molecule may have no or many
thermfits.
thermset
Short for "thermodynamic set". A collection of user-defined
groups of thermfits. Each thermfit corresponds to a unique molecule,
so that a molecule is represented only once within a thermodynamic
set.