info is the primary function used for querying the thermodynamic database (thermo$obigt). In common usage, it is called recursively; first with a character value (or values) for species indicating the name(s) or formula(s) of the species of interest. The result of this call is a numeric value, which can be provided as an argument in a second call to info in order to retrieve a data frame of the thermodynamic properties of the species. For its work, info calls on the other functions that are described below, which unlike info all expect arguments with length=1. info.character searches for matches of the indicated species to names, chemical formulas, and abbreviations (in the abbrv column) in the thermodynamic database. If the text of the species is matched the index of that species is returned. If there are multiple matches for the species and state is NULL, the index of first match is returned. The order of entries in thermo$obigt is grouped by states in the order aq, cr, gas, liq, so for species in both aqueous and gaseous states the index of the aqueous species is returned, unless state is set to gas. The two exceptions are species identified by O2 or oxygen (which without any indicated state matches the gaseous species) and H2O (which matches the liquid species even if the indicated state is aq). Normally, if a species match can not be located, the function then looks for proteins with the name of species (using iprotein), computes its properties if found (ip2aa) and adds this to the thermodynamic database (mod.obigt). check.protein prevents the processing of proteins and is provided to avoid an infinite loop in the interaction with mod.obigt.
info.character has additional logic for dealing with proteins and with multiple matches for the cr state. If the state is cr, matches will be counted for states entered as cr1, cr2 etc in the database, and all of the species indices will be returned. Note, however, that info only ever returns a single species index, which becomes NA in the case of multiple matches to cr. This functionality of info.character is used in subcrt to handle minerals with phase transitions.
Names of species including an underscore character are indicative of proteins, e.g. LYSC_CHICK. If the name of a protein is provided to info.character and the composition of the protein can be found using protein, the thermodyamic properties and parameters of the nonionized protein (calculated using amino acid group additivity) are added to the thermodynamic database. Included in the return value, as for other species, is the index of the protein in the thermodynamic database or NA if the protein is not found. Names of proteins and other species can be mixed.
info.approx searches the database for similar names or formulas using agrep. If one or more of these is found, the results are summarized on the screen, and the indices of the approximately matching species are returned. Species that have no approximate matches are indicated by NA in the return value. When invoked by info, the latter function accepts the species index only for a single approximate match; multiple matches are translated to NA.
info.numeric returns the rows of thermo$obigt indicated by ispeices, after removing any order-of-magnitude scaling factors. If these species are all aqueous or are all not aqueous, the compounded column names used in thermo$obigt are replaced with names appropriate for the corresponding equations of state. A missing value of one of the standard molal Gibbs energy (G) or enthalpy (H) of formation from the elements or entropy (S) is calculated from the other two, if available. If check.it is TRUE, several checks of self consistency among the thermodynamic properties and parameters are performed using checkGHS and checkEOS (this depends on the completeness of the data entry).