  Irradiation- and collision-induced fragmentation studies provide information
about geometry, electronic properties and interactions between structural units
of various molecular systems. Such knowledge brings insights into
irradiation-driven chemistry of molecular systems which is exploited in
different technological applications. An accurate atomistic-level simulation of
irradiation-driven chemistry requires reliable models of molecular
fragmentation which can be verified against mass spectrometry experiments. In
this work fragmentation of a tungsten hexacarbonyl, W(CO)$_6$, molecule is
studied by means of reactive molecular dynamics simulations. The quantitatively
correct fragmentation picture including different fragmentation channels is
reproduced. We show that distribution of the deposited energy over all degrees
of freedom of the parent molecule leads to thermal evaporation of CO groups and
the formation of W(CO)$_n^+$ ($n = 0-5$) fragments. Another type of fragments,
WC(CO)$_n^+$ ($n = 0-4$), is produced due to cleavage of a C--O bond as a
result of the localized energy deposition. Calculated fragment appearance
energies are in good agreement with experimental data. These fragmentation
mechanisms have a general physical nature and should take place in
radiation-induced fragmentation of different molecular and biomolecular
systems.
