Reactants are the reactants in the reaction string (left side of equation). One or more can be specified. "+" sign is optional.

Products are the products in the reaction string (left side of equation) One or more can be specified. "+" sign is optional.

Reaction Class is a notation classifying the type of reaction. For example, C-H+O means

abstraction of H from a carbon center

by a oxygen-centered radical. For more information, go to the main "HELP" menu (click on tab in upper right corner of page) and then elect help on Reactions.

Reaction Sites is a notation classifying the type of reaction sites involved. For example, C-H+C [CH3-Cd/CH2] would describe the reaction
CH₃-CH=CH₂ + CH₃CH₂ = CH₂=CH-CH₂* + C₂H₆
(Propene + Ethyl = Allyl + Ethane).

"C-H+C" is the Reaction Class and "CH3-Cd/CH2" are the reaction sites.

The "C-H" is being abstracted from a CH3 (methyl group) that is adjacent to a double bonded carbon (Cd).

"C-H" is being abstracted by a methylene radical group "CH2" (e.g. CH3CH2* or RCH2*)

For more information, go to the main "HELP" menu (click on tab in upper right corner of page) and then elect help on Reactions.

Stoichiometry is Hill-sorted order molecular formula for the reactions. Atom counts of ONE are EXPLICIT (e.g. Stoichiometry[O2+H=O+OH] = H1O2).

Reaction Datatype is notation describing the type of data, or conditions. Multiple info should be semicolon delimited. Examples of datatype are "review", "review-ltd", "shock", "est", "rrkm", "abinitio", "tlo", etc.
Examples of conditions are "P=1 atm".
Examples of relative rate expressions are

shock; rel C2H6+H=C2H5+H2

flame; rel Naphthalene+OH=Naphth2yl+H2O A*2 E+2 kcal

Select Models enables one to identify select or "favorite" models. This way, when searching, one doesnt have to get reactions from every single model - by selecting "favorite" models, searches can be restricted to a single model, or a group of selected/favorite models.

To select a model as a "favorite", search for the model, then simply click on "Add to Select/Favorite Models". If you want to deselect the model, simply click on "Delete from Select/Favorite Models"

Note: in order to compare models, one must select two models. If more than two are selected, then the first two on the list are used.

Reaction Sub System is a user defined reaction system within a model (or submodel). For example a PAH formation submodel, may be further subdivided into Naphthalene chemistry, Pyrene chemistry, Coronene chemistry, etc.

Reaction Sub Models are sub models (sub mechanisms) that have been added to this models. For example, a butane reaction set may contain submodels for Hydrogen/Oxygen chemistry, C1-C2 chemistry, low temperature butane ignition chemsitry, PAH formation chemistry, etc.

Units: Different choices of units for A factor (prexponential) and E (activation energy)

Search forward AND reverse means that the search will consider reactions both as written (forward) AND those written in the reverse direction.

Exact Match:
Checked - means search terms are matched exactly for entire field.
NOT Checked - means partial matches to search terms are found. e.g. "ethan" will find "ethane", "ethanol", as well as "methane"
e.g. "C2H" will find "C2H1", "C2H6", as well as "C2H6O1"

Display Images means gif images (if exist) of the molecules will be displayed along with the reaction string.

Use Orig Symbols means that the original symbols in the uploaded reaction set will be used (e.g. aC3H4).
Default is using database "preferred" symbols (e.g. propadiene).

Reaction is the Reaction string ReacA + ReacB = ProdC + ProdD

Clicking on equals sign (=) will search for all reactions with that set of reactants and products as written, or reverse

Reaction Class is a notation classifying the type of reaction. For example, C-H+O means abstraction of H from a carbon center (C-H bond being broken) by a oxygen-centered radical (H+O bond being formed) Reaction Sites is a notation classifying the type of reaction sites involved. For example, C-H+C [CH3-Cd/CH2] would describe Propene + Ethyl = Allyl + Ethane. "C-H+C" indicates it is an abstraction reaction. "CH3-Cd" means that the C-H is being abstracted from a methyl group that is adjacent to a double bonded carbon. "CH2" means that the C-H is being abstracted by a methylene radical group (RCH2*).

For more information, go to the main "HELP" menu (click on tab in upper right corner of page) and then select help on Reactions.

A is Arrhenius parameter preexponential

b is the (extended) Arrhenius parameter temperature exponent

E is the Arrhenius parameter activation energy

Reaction Reference is the ORIGINAL literature reference for the specific reaction rate expression.

Clicking on left side of Reaction Reference will pull up the bibliographic record

Clicking on right side of Reaction Reference will search for all reaction records with this reference

Reaction Datatype is notation describing the type of data, or conditions. Multiple info should be semicolon delimited. Examples of datatype are "review", "review-ltd", "shock", "est", "rrkm", "abinitio", "tlo", etc.
Examples of conditions are "P=1 atm".
Examples of relative rate expressions are

shock; rel C2H6+H=C2H5+H2

flame; rel Naphthalene+OH=Naphth2yl+H2O A*2 E+2 kcal

Model Reference is the Model ID (e.g. 1979-Methanol-WestbrookDryer) for the model/mechanism that contains the specific reaction rate expression.

Clicking on left side of Model Reference will pull up the model record

Clicking on right side of Model Reference will search for all reaction records with this model reference

Reaction Sub Models are sub models (sub mechanisms) that have been added to this models. For example, a butane reaction set may contain submodels for Hydrogen/Oxygen chemistry, C1-C2 chemistry, low temperature butane ignition chemsitry, PAH formation chemistry, etc.

Reaction Sub System is a user defined reaction system within a model (or submodel). For example a PAH formation submodel, may be further subdivided into Naphthalene chemistry, Pyrene chemistry, Coronene chemistry, etc.

Kinetics Database are links to this reaction (if exists) in the NIST Chemical Kinetics Database.

Stoichiometry is Hill-sorted order molecular formula for the reactions. Atom counts of ONE are EXPLICIT (e.g. Stoichiometry[O2+H=O+OH] = H1O2).

Reverse Params means reverse rate expressions /REV/ are displayed if given in reaction set

Low Press Params means low pressure parameters are displayed if given in reaction set.

FallOff means falloff parameters are displayed if given in reaction set.

Troe parameters means Troe falloff parameters are displayed if given in reaction set.

SRI parameters means SRI falloff parameters are displayed if given in reaction set.

A and B (same rates): when checked will search for all reactions that are contained in both of two selected models (see note 1), and have the same rate expressions (see note 2).
Note 1: the first two models listed in one's SELECTED MODELS ("favorite") will be compared.
Note 2: Default threshold for "same" rate expression is a (log) averaged ratio of less than 2.0 over 800-1500
Note 3 : ALL reactions that meet these criteria are listed (not just 25 at a time) in results page, because of code limitations for now. Ignore (for example) "Results 1 - 109 of 109". In this case, 109 is the TOTAL number of "A and B", not just the subset "A and B (same rates)". The correct count can be found in the left hand column.

A and B (different rates) when checked will search for all reactions that are contained in both of two selected models (see note 1, but have different rate expressions (see note 2.
Note 1: the first two models listed in one's SELECTED MODELS ("favorite") will be compared.
Note 2: Default threshold for "different" rate expression is a (log) averaged ratio of greater than 2.0 over 800-1500
Note 3 : ALL reactions that meet these criteria are listed (not just 25 at a time) in results page, because of code limitations for now. Ignore (for example) "Results 1 - 109 of 109". In this case, 109 is the TOTAL number of "A and B", not just the subset "A and B (different rates)". The correct count can be found in the left hand column.

A and B (written reverse) when checked will search for all reactions that are contained in both of two selected models, but are written in different directions.
For example, C₂H₆ = CH₃ + CH₃ versus CH₃ + CH₃ = C₂H₆.
Note: the first two models listed in one's SELECTED MODELS ("favorite") will be compared.

A not B when checked will search for all reactions contained in reaction set A, but NOT found in reaction set B (written in neither "forward" nor "reverse" direction).
Note: the first two models listed in one's SELECTED MODELS ("favorite") will be compared.

B not A when checked will search for all reactions contained in reaction set B, but NOT found in reaction set A (written in neither "forward" nor "reverse" direction).
Note: the first two models listed in one's SELECTED MODELS ("favorite") will be compared. To SELECT models as "favorites"