  We report specific heat capacity measurements on a LiFeAs single crystal at
temperatures down to 400 mK and magnetic fields up to 9 Tesla. A small specific
heat jump at Tc and finite residual density of states at T=0 K in the
superconducting (SC) state indicate that there are strong unitary scatterers
that lead to states within the SC gap. A sub-linear magnetic field dependence
of the Sommerfeld coefficient \gamma(H) at T=0 K is equally well fitted by both
a nodal d-wave gap as well as a sign changing multiband \pm s-wave gap. When
impurity effects are taken into account, however, the linear temperature
dependence of the electronic specific heat C_{el}/T at low temperatures argues
against a nodal d-wave superconducting gap. We conclude that the SC state of
LiFeAs is most compatible with the multiband \pm s-wave SC state with the gap
values \Delta_{small}=0.46 \Delta_{large}.
