Don't try to derive nonperiodic halos if the periodic halos don't exist
Don't try to derive nonperiodic halos if the periodic halos don't exist

iakovos-panourgias/fluidity,jjo31/ATHAM-Fluidity,rjferrier/fluidity,jrper/fluidity,iakovos-panourgias/fluidity,iakovos-panourgias/fluidity,rjferrier/fluidity,rjferrier/fluidity,jrper/fluidity,iakovos-panourgias/fluidity,jrper/fluidity,iakovos-panourgias/fluidity,jjo31/ATHAM-Fluidity,jjo31/ATHAM-Fluidity,rjferrier/fluidity,jjo31/ATHAM-Fluidity,jrper/fluidity,jrper/fluidity,rjferrier/fluidity,jjo31/ATHAM-Fluidity