MOLPRO

3 DEFINITION OF MOLPRO INPUT LANGUAGE 10
3.5 Options
Options have the general form NAME[=value]
where value can be a number, and expression, or a string. Several options are separated by
comma or blank. NAME must begin with a character [A-Z]. If options are given on a COMMAND
line or on directives within a command block, they are valid only for the corresponding program
(see Sec. 3.3). If options are given in a procedure, they are valid only in the procedure and
procedures called from the current procedure; whenever a procedure is terminated, the options
of the previous level are restored.
Options can also be single keywords, like SYM or NOSYM. In this case, the option is switched
on or off, depending whether or not the key begins with NO. Alternatively, such logical options
can also be set or unset using NAME=ON or NAME=OFF. For instance, SYM=OFF is equivalent
to NOSYM. Furthermore, YES and NO are aliases for ON and OFF, respectively.
3.6 Data
Data are defined as a sequence of numbers, expressions, or strings, separated by commas or
blanks. Generally, the order of data is essential. Empty fields are interpreted as zeros. Strings
and variables must begin with a character [A-Z]. If + or − follows blank and directly precedes
a number or variable it is interpreted as sign and not a binary operator. If there are no blanks
before and after such operators, or blanks follow them, they are interpreted as binary operators.
Examples:
3 - 4 4 yields [-1,4]
3-4 4 yields [-1,4]
3 -4 4 yields [3,-4,4]
3,-4 4 yields [3,-4,4]
3, -4, 4 yields [3,-4,4]
Expressions (including numbers) may contain variables.
Examples for the use of data: geometry and basis input, LATTICE, OCC, CLOSED, CORE, WF
directives.
In some cases several lines of data are needed for a certain command or directive; in such cases
the data must follow directly the corresponding command|directive, and must be enclosed in
square brackets:
COMMAND,options
[data]
Normally, the input format of data is MOLPRO style, i.e., numbers are separated by commas,
and variables as well as expressions can be used.
If data are included using external files, the input format of data is free format: no commas are
needed, but no variables and expressions can be used.
3.7 Expressions
In any input field, data can be entered in the form of expressions. Numbers and variables are
special cases of expressions. An expression is typed in Fortran style and may contain any number
of nested parenthesis. The standard intrinsic functions are also available (see next section).