  Using Car-Parrinello molecular dynamics calculations we investigate the
behavior of the low-dimensional multiorbital Mott insulator TiOCl under
pressure. We show that the system undergoes {\it two} consecutive phase
transitions, first at $P_\text{c}$ from a Mott-insulator to a metallic phase in
the $ab$ plane with a strong Ti-Ti dimerization along $b$. At a pressure
$P'_\text{c} > P_\text{c}$ the dimerization disappears and the system behaves
as a uniform metal. This second transition has not yet been reported
experimentally. We show that the insulator-to-metal transition at $P_\text{c}$
is driven by the widening of the bandwidth rather than structural changes or
reduction of crystal field splittings and it shows a redistribution of the
electronic occupation within the $t_{2g}$ bands. Our computed
pressure-dependent lattice parameters are consistent with experimental
observations and the existing controversy on the change of crystal symmetry at
high pressures is discussed.
