  Energetically minimum configurations of the first- and second-nearest
neighbor (NN) CO2 molecules surrounding a vacancy, created by removing a single
molecule from the Pa3 structure, were calculated by use of the Monte Carlo
simulation technique at zero temperature. It was found that among the 1st NN
molecules, only six NN molecules, closest to the oxygen atoms of the removed
CO2 molecule, significantly changed the positions and orientations, while the
other six molecules were not influenced by the creation of the vacancy. The
configurations of the molecules no longer had the three-fold symmetry that the
Pa3 structure possessed. The influence of the vacancy on the 2nd NN molecules
was relatively small.
