  We investigate a bilayer honeycomb lattice model of spin-1/2 fermions at
half-filling with local Heisenberg coupling of fermion spins across the two
layers. Using variational Monte Carlo (VMC) simulation, we demonstrate that the
system undergoes a direct transition from a Dirac semimetal phase to a
symmetric gapped phase, known as symmetric mass generation (SMG), as the
Heisenberg coupling strength is increased. The transition does not involve
spontaneous symmetry breaking or topological order and has been proposed as an
example of the fermionic deconfined quantum critical point (fDQCP). Our
simulation shows that a fermionic parton bilinear mass opens at the transition
point while all symmetries are still preserved thanks to the quantum
fluctuations introduced by the correlation factor in the variational wave
function. From the simulation data, we extract the critical exponent
$\nu=0.96\pm0.03$ and the fermion scaling dimension $\Delta_c=1.31\pm0.04$ at
the SMG critical point, which are consistent with the field theoretical
prediction of fDQCP in (2+1)D. These findings support the hypothesis that the
fermion fractionalizes at the SMG critical point.
