Preliminary
Comments - Data Input
DMAREL uses a free format input processor. Each line of data is read in
as characters, which make up a number of data fields separated by one
or more spaces. By default 80 characters per line are read in, although
this may be reduced using the
IREC directive. (See section
IREC) The characters are then interpreted
as literal (character string) constants, integers or real numbers. Literals
are input as a string of characters of which at least one must be alphabetic.
There cannot be any embedded spaces in the constant. Only the first four
characters will be interpreted by the program. This is important
when assigning names to atoms, as names of different atoms must differ
in the first four characters of the name for the name to be unique. For
determining which short range potential to use, only the first two
characters are used. Integer constants are input as a signed or
unsigned integer, which again must not contain any embedded spaces. All
keywords are entered in capital letters, lower case input of keywords
will not be recognised. Since only the first four letters are used to
define each directive, it is possible to make the input clearer by using
more lengthy keywords. For example, BASIs_atoms
instead of simply BASI
for the atom position input. Note that if this is used, do not leave gaps
between sections of your keywords since the program will assume that two
data items have been input and give an error.
Real constants may only be input in the F format, and the E format is prohibited. A real constant will therefore consist of an optional sign, followed by a floating point number containing a decimal point. Again there should be no embedded spaces, and the . should always be included.
There is no end of record error message, so that attempting to read past the end of a line will not cause an error. If the program tries to read a literal constant and there are no more data fields in the record, four blank characters are input. Similarly for an integer the value 0 is input and for a real number the value 0.0.
Error Messages
INPUT ERROR TYPE 1
The input processor encountered an invalid character in an integer data field.
INPUT ERROR TYPE 2
The input processor encountered an invalid character in a real data field.
These are both non-fatal errors, the program may carry on in order to try to find further errors.
END OF INPUT DATASET ENCOUNTERED. PROGRAM TERMINATING
This is a fatal error
- the input dataset is too short.