  A Monte Carlo computer simulation algorithm in classical phase space is given
for the treatment of quantum systems. The non-commutativity of position and
momentum is accounted for by a mean field approach and instantaneous effective
harmonic oscillators. Wave function symmetrization is included at the dimer and
double dimer level. Quantitative tests are performed against benchmarks given
by Hernando and Van\'i\v{c}ek (2013) for spinless neon--parahydrogen, modeled
as interacting Lennard-Jones particles in a one dimensional harmonic trap. The
mean field approach is shown to be quantitatively accurate for high to moderate
temperatures $\beta \hbar \omega_\mathrm{LJ} < 7$, and moderate densities,
$\rho \sigma \approx 1$. Results for helium show that at the lowest temperature
studied, the average energy is about 4\% lower for bosons than for fermions. It
is argued that the mean field algorithm will perform better in three dimensions
than in one, and that it will scale sub-linearly with system size.
