  Implicit-solvent models are widely used to study the electrostatics in
dissolved biomolecules, which are parameterized using force fields. Standard
force fields treat the charge distribution with point charges, however, other
force fields have emerged which offer a more realistic description by
considering polarizability. In this work, we present the implementation of the
polarizable and multipolar force field AMOEBA, in the boundary integral
Poisson-Boltzmann solver \texttt{PyGBe}. Previous work from other researchers
coupled AMOEBA with the finite-difference solver APBS, and found difficulties
to effectively transfer the multipolar charge description to the mesh. A
boundary integral formulation treats the charge distribution analytically,
overlooking such limitations. We present verification and validation results of
our software, compare it with the implementation on APBS, and assess the
efficiency of AMOEBA and classical point-charge force fields in a
Poisson-Botlzmann solver. We found that a boundary integral approach performs
similarly to a volumetric method on CPU, however, it presents an important
speedup when ported to the GPU. Moreover, with a boundary element method, the
mesh density to correctly resolve the electrostatic potential is the same for
stardard point-charge and multipolar force fields. Finally, we saw that
polarizability plays an important role to consider cooperative effects, for
example, in binding energy calculations.
