energy <energy-statement> end
<energy-statement> :==
[accumulate=print|energy|reset]
If no accumulate is specified or accumulate=energy is specified,
the energies will be computed, printed and accumulated. If
accumulate=reset is specified the energy accumulation variables
are reset without performing an energy calculation. If
accumulate=print is specified accumulation information is printed
without performing an energy calculation. The result of the
calculation is also stored in symbols with the same name as the
individual energy terms: $ener, $vdw, $elec, etc.