8.1 Setting variables

A variable can be defined using

variable1=value1, variable2=value2, ...

A variable definition is recognized by the equals sign in the first field of the input card. For example,


does not define variables; here ENERGY and GRADIENT are options for the THRESH directive.

Variables can have different types:

The value is a number or an expression. The general form of value is
expression [,] [unit]
unit is an optional string which can be used to associate a unit to the value. ANG[STROM], DEGREE, HARTREE are examples. Undefined variables in expressions are assumed to be zero (and defined to be zero at the same time).
The value can be .TRUE. or .FALSE. (.T. and .F. also work), or a logical expression. Internally, .TRUE. is stored as 1 and .FALSE. as zero.
The value can either be a string enclosed in quotes or a string variable. See section 8.3 for more details.

molpro@molpro.net 2018-09-24