  Disordered quantum antiferromagnets in two-dimensional compounds have been a
focus of interest in the last years due to their exotic properties. However,
with very few exceptions, the ground states of the corresponding Hamiltonians
are notoriously difficult to simulate making their characterization and
detection very elusive, both, theoretically and experimentally. Here we propose
a method to signal quantum disordered antiferromagnets by doing exact
diagonalization in small lattices using random boundary conditions and
averaging the observables of interest over the different disorder realizations.
We apply our method to study a Heisenberg spin-1/2 model in an anisotropic
triangular lattice. In this model, the competition between frustration and
quantum fluctuations might lead to some spin liquid phases as predicted from
different methods ranging from spin wave mean field theory to 2D-DMRG or PEPS.
Our method accurately reproduces the ordered phases expected of the model and
signals disordered phases by the presence of a large number of quasi degenerate
ground states together with the absence of a local order parameter. The method
presents a weak dependence on finite size effects.
