                  NIST Standard Reference Database 25 
                         Structures and Properties   
                        Version 2.02, January 1994

                 Data Compiled, Formatted and Evaluated 
                                  by 
Sharon G. Lias, Joel F. Liebman, Rhoda D. Levin, and Sherif A. Kafafi
        for the Chemical Kinetics & Thermodynamics Division of NIST

                                  - 
                   "Structures and Properties" Software
                                  by
                            Stephen E. Stein

             Distributed by the Standard Reference Data Program
   National Institute of Standards and Technology, Gaithersburg, MD 20899
 
           Copyright 1991,1994 by the U.S. Secretary of Commerce
                 on behalf of the United States Government
 
DISCLAIMER: NIST uses its best efforts to deliver a high quality copy of
the Database and to verify that the data contained therein have been 
selected on the basis of sound scientific judgement.  However, NIST makes
no warranties to that effect, and NIST shall not be liable for any damage
that may result from errors or omissions in the Database
%ERROR
0x0104  Disk I/O error 1.  Is a disk nearly full?
0x0105  Disk I/O error 2.  Invalid RAM Drive (TMP=) or disk nearly full?
0x0106  RAM error.  Remove memory resident programs.
0x0107  Expanded memory error 1.  More space is required.
0x0108  Expanded memory error 2.  More space is required.
0x0109  Expanded memory error 3.  More space is required.
0x0202  Could not find valid font file (MD_FONT.ISS or LG_FONT.ISS)
0x0501  Insufficient RAM was available.  Remove memory resident programs.
0x0701  Out of RAM?  Could not access all of memory?
0x0704  Could not read a file.
0X0705  Could not write a file (Disk Full?).
%MAIN
The program retrieves ionization energy (also called ionization potential) 
   and appearance energy (appearance potential) data and also retrieves and 
   estimates chemical thermodynamic properties of gas phase species.  Data 
   may then be used for calculating equilibrium constants.  Estimates of 
   boiling points, vapor pressures and critical constants may also be made 
   using structural information and built-in estimation methods.
 
To draw a structure so that you can find and/or estimate its properties,
   select DRAW.  Otherwise, data can be located by selecting SEARCH.
   SEARCH may also be selected from the REACTION screen.
 
After selecting SEARCH, literature data for a particular chemical compound 
   can be retrieved by chemical name or Registry Number, or by entering the
   chemical formula and selecting the compound of interest from a screen 
   displaying chemical structures for the set of isomers. From the SEARCH 
   screen it is also possible to retrieve all data pertaining to the 
   appearance energies of a particular fragment ion generated from different 
   precursor molecules;  to activate this search, type in the formula of the 
   ion with a "+" sign at the end.  [Example: CH3+].  By selecting the 
   search by ionization energy (or ionization potential as the ionization 
   energy is called on the screen), you are given access to the entire 
   database sorted according to value of the ionization energy.  To search 
   by molecular structure, you must first have drawn and saved a molecular 
   structure drawing.
 
A set of molecules having specified elemental composition may be found
   with the formula search.  This may be done by entering one or more
   specifications.  Each specification consists of an element, a symbol
   (> < = !) and the number of atoms of the element (an integer).
   The symbols allowed are: > (greater than), < (less than), = (equal to)
   and ! (not equal to).  Each specification should be separated by a space.
   For example, to find all species having between 5 and 10 carbon atoms
   and 2 chlorine atoms, enter: C>4 C<11 Cl=2.
 
To estimate the properties of a molecule not in the database, you must
   first DRAW the molecule.  After drawing, select 'Done' and then 
   'Estimate' to estimate properties.  If an equivalent structure is in 
   the database, its name and properties will also be shown.  Also, to 
   search the database for all compounds containing a "substructure", 
   select DRAW to compose the substructure.  Then, select 'Done' followed 
   by 'Substructure' to find all structures containing the fragment drawn.
 
Select SEARCH, then 'Structure' to view a list of structures that you 
   have previously drawn.  NOTE: The default name for a structure-drawing 
   file is "LATEST".  If you use the default name, any earlier structure 
   drawing saved under "LATEST" will be overwritten.  Hits from the last 
   substructure search may be viewed by selecting the special file SUB.STR.
 
If you wish to estimate equilibrium constants, reaction enthalpies, or 
   compare data for different molecules, select REACTION, then add species 
   you want to work with to a List.  Species are added to the List by 
   selecting SEARCH from the REACTION screen, and then carrying out a search 
   by name, formula, Registry Number, etc. using the usual procedures; the 
   compounds selected will appear on the List, from which they can be 
   selected for building reactions and comparing properties.  Simply 
   indicate a compound on the list using the cursor or mouse and you will 
   be prompted to identify the species as a "reactant" or "product".
 
In the OPTIONS submenu you may select to have data viewed in units of 
   kilojoules or kilocalories.  You may also choose whether a search will 
   end with a viewing of a screen showing thermochemical data for the 
   neutral molecule (choose NEUTRAL) or a listing of ionization/appearance 
   energy data (choose ION).  If you wish to create reactions containing 
   ionic species, you must select ION.

To exit this program, select QUIT.
%RXN
This is the REACTION THERMODYNAMICS screen.
The upper half of the screen shows the reaction.  Reaction thermodynamics
  are shown at the bottom of this section if the reaction is balanced.
  If not, elements needed to balance the reaction are shown.
The lower half of the screen shows a list of species, formulas and a
  summary of the thermodynamic data for the species.  Estimated and 
  literature enthalpy values are shown.  To enter a species in a reaction, 
  it must first be added to this list.
 
ADDING TO LIST:
  To add a molecule to the List, carry out a standard SEARCH starting from 
  the REACTION screen.  Searching here is the same as from the opening menu, 
  except that DATA screens are not shown -- instead selected species are 
  simply added to the list. If you selected "Ion" from the OPTIONS available 
  from the Opening Screen, you will be given the choice between adding the 
  thermochemical information for the ion or for the neutral molecule.  Note 
  that only species for which experimental or estimated thermodynamic data 
  are contained in the database can be added to the list.  If you want to 
  add a molecule for which no thermodynamic data appear in the database, 
  you can only do so by supplying your own estimated data; you do this by 
  accessing the molecule through a SEARCH from the OPENING screen, then 
  indicate 'ESTIMATE', and choose the box labeled 'Add Your H,S'.

USING THE LIST:
Press the number of the species or click the mouse over the species
  in the list and a box will appear which will present you with the 
  following choices:
1) Add the species to the reaction at the upper part of the screen as 
   either a reactant or product, and specify the stoichiometry.
2) Omit the species from the reaction.
3) Delete the species from list (and reaction).
4) View the original data for the species.
 
THERMODYNAMICS:
If the reaction is balanced and both entropies and enthalpies are
   available, select this to view logarithms of equilibrium constants as 
   a function of temperature.
 
PRINTING:
Selecting this option will bring up a menu where you may print the screen,
   print all information concerning a reaction that you have created, or
   store this information in a disk file.
  
OTHER:
A species may be deleted from the reaction by using a mouse to indicate 
  the species, and then pressing OKAY.
If you need to draw a molecule, do it from the opening menu.
The current reaction may be deleted by selecting 'New Reaction'.
%DRAWDATA

This screen shows the structure that you have drawn (upper left), and a
    version of this structure showing equivalent atoms (upper right).
    Any atoms having the same number in the latter are equivalent.
 
Estimated data are shown below the structure.  The Groups used and 
    Corrections applied are also shown.  If a structure was found in the 
    database that matched the drawn structure, select DB Data to view it.  
    For certain species, the program will be unable to provide a good 
    estimate.  This will happen, for example, if the molecule contains 
    atoms for which estimation parameters have not been derived, or if    
    the molecule contains certain ring configurations.  In this event, 
    the program will give you a message informing you of the problems or 
    limitations.
 
The CORRECTIONS data are the most complex.  Abbreviated names for any
    ring corrections are shown along with correction values.  The
    rotational symmetry number is broken into methyl and non-methyl
    contributions.  Corrections for optical isomers [n(o.i.)] are
    discussed in the documentation.  To ensure that symmetry numbers
    are computed correctly for complex rings, use the IN/OUT bond
    types when drawing them.
 
All of Benson's corrections are used, including various gauche, cis and
    ortho interactions.  Numbers of interactions and their net effect
    on the enthalpy of formation are also shown.
 
If molecules have groups or rings not present in the estimation list you
   may enter your own values by selecting 'Est.' and then 'Add Your H,S',
   and then typing in your values.
 
Estimates of vaporization and boiling point data may be made for most
   species using the Joback method (see Documentation).  Fair accuracy
   (a few degrees in an estimated boiling point, for instance) can only
   be expected if you have one vaporization point (that is, a known 
   temperature and the vapor pressure at that temperature).  Otherwise,
   only a coarse boiling point estimate is possible that can be in error
   by 20 degrees or more.
 
PRINTING:
Selecting this option will bring up a menu where you may print the screen,
   print all thermodynamic information concerning a species, or
   store this information in a disk file.
%DBDATA

This is the DATA SCREEN, showing literature and estimated chemical
    thermodynamic data for a single substance.  Some data is shown
    in the upper portion of the screen, while other data may be shown
    in the lower portion.
 
To find the groups underlying the thermochemical estimates,
    select GROUPS; to view any corrections used, select CORRECTIONS.  
 
The CORRECTIONS data are the most complex.  Abbreviated names for any
    ring corrections are shown along with correction values.  The
    rotational symmetry number is broken into methyl and non-methyl
    contributions.  Corrections for optical isomers [n(o.i.)] are
    discussed in the documentation.  To ensure that symmetry numbers
    are computed correctly for complex rings, use the IN/OUT bond
    types when drawing them.
 
All of Benson's corrections are used, including various gauche, cis and
    ortho interactions.  Numbers of interactions and their net effect
    on the enthalpy of formation are also shown.
 
Literature references, if available, may be viewed by selecting 'Ref'.
   Note that many of the references refer to secondary sources 
   (not the original source).  The most common reference is 88LIE.
   These values have been estimated by Prof. Joel Liebman using the method
   of Macroincrementation (see Documentation).
 
If molecules have groups or rings not present in the estimation list you
   may enter your own values by selecting 'Est.' and then 'Your own H,S',
   and then typing in your values.
 
Estimates of vaporization and boiling point data may be made for most
   species using the Joback method (see Documentation).  Fair accuracy
   (a few degrees in an estimated boiling point, for instance) can only
   be expected if you have one vaporization point (that is, a known 
   temperature and the vapor pressure at that temperature).  Otherwise,
   only a coarse boiling point estimate is possible that can be in error
   by 20 degrees or more.
 
PRINTING:
Selecting this option will bring up a menu where you may print the screen,
   print all thermodynamic information concerning a species, or
   store this information in a disk file.
%NOCT
 
The structure of this species is not in the database and an estimate is
     not possible.  This will occur when the structure is trivial
     (an H-atom, for instance) or if the structure was not available
     for this release.
 
You may enter an estimate of the heat of formation and entropy by selecting
     "Estimate" and then typing in the value(s).  These values may be used
     for equilibrium calculations as well as for later reference.
 
PRINTING:
Selecting this option will bring up a menu where you may print the screen,
   print all thermodynamic information concerning a species, or
   store this information in a disk file.
%STRUS
 
This is the "Summary" list showing all the 'hits'.  Unless this screen was 
     reached from the REACTION screen, you may view the data for a species
     by either entering its number (1-9) or clicking on the structure with 
     a mouse.  A count of the total number of hits and and numbers of 
     those shown is displayed on the bottom line.
 
If this screen was reached from the REACTION screen, selections will
     simply be added to the reaction list.  Data may be viewed later
     from the REACTION screen by selecting the VIEW option after
     selecting this species.
 
If any species is too large to be drawn, select Resize to increase its
     size (a second Resize command will restore the original size).
 
Page forward with NEXT, backward with PREVIOUS and return to the first
     screen with FIRST.  The PgDn and PgUp keys may also be used to
     page forward or backward.
 
Selecting PRINT will bring up a menu where you may print the screen,
   print the names of all "Hits" or store this information in a disk file.

Pressing QUIT will return to the previous level; this screen will be lost.
 
