The energy statement performs a single calculation of all energy terms that are turned on. The atomic forces are also computed and stored in arrays DX, DY, and DZ (see vector-statement, Section 2.16).
Each time this statement is issued, it performs an accumulation of the partial energy terms. Average and rms values of the accumulated energy terms can also be printed by using this statement.
Upon completion of the energy calculation, symbols are declared that contain the computed energy terms. The name of the symbols is given by $<energy-term> (see Section 4.5). The overall energy (Eq. 4.1) is stored in the symbol $ENER; the rms gradient is stored in $GRAD. The value of the second energy function (Eq. 4.26) is returned in the symbol $PERT.