6.2 Input format

MOLPRO's execution is controlled by an input file. In general, each input record begins with a keyword, which may be followed by data or other keywords. The input is read sequentially by a controlling program; when the controlling program calls a program module, this module continues to read the input file until it finds an unknown keyword. After the module has performed its function, control is returned to the controller.

The input file can be written in free format. The following conversions take place:

, (comma)

move to next tab stop, i.e. this delimits input fields

; (semicolon)

end of record, i.e. a new record is started

! (exclamation mark)

ignore rest of input line (useful for comments)

-- (three dashes)

end of file (rest of input is ignored)

You may type your input upper or lower case. The input processor will convert all characters to upper case. All integers are appended with ``.'' (only floating point numbers are read by the program).

Several logical input records can actually be typed on one line and separated by semicolons, i.e., a given input line may contain many actual commands (separated by semicolons), or just one, as you prefer. These basic command units (records) delimited by semicolons are also frequently referred to as cards throughout this manual.

Exception to these general rules are:

***

first data line always

INCLUDE

include other input file

FILE

definition of named files

TEXT

prints text

TITLE

defines a title for the run

CON

specifies orbital configurations

--

last line of input

These commands always occupy a whole line. Using INCLUDE it is possible to open secondary input files. If an INCLUDE command is encountered, the new input file is opened and read until its end. Input is then continued after the include card in the first file. INCLUDE's may be nested.

A MOLPRO input record (card) contains a number of input fields. Input fields may be up to 256 characters wide and contain either expressions or strings. The fields can be separated by commas or blanks. However, commas are required in certain cases to make the meaning unique. For instance, typing 3 +4 evaluates to one field with value 7, but 3, +4 is the input for two fields with values 3 and 4. We recommend the general use of commas in order to avoid unexpected results.

Each line may start with a label. A label is separated from the body of the line by a colon (:). The colon is part of the label. The length of the label must not exceed 6 characters (including the colon) and the labels must be unique. Labels may be useful with GOTO commands. Example:

GOTO,START:
...
START: CCSD(T)

Here START: is a label, and CCSD(T) is a command.

Strings containing blanks can be entered using quotes. For instance, 'This is a string' is interpreted as one string, but This is a string is a sequence of four strings in four subsequent fields. Strings in quotes are not converted to upper case.

Input lines may be concatenated using $\backslash$ at the end of the line(s) to be continued. Any number of lines may be concatenated up to a total length of 1024 characters (only 500 characters are possible on older IBM systems).

Filenames may be up to 31 characters long, provided that long filenames are supported by the Unix system used. An exception are older CRAY systems, which allow only 8 characters for the names of binary MOLPRO files.