It is possible to generate pseudopotentials and basis functions for a virtual atom with fractional nuclear charge. The relevant keywords in ADPACK are given by
AtomSpecies 6.2 total.electron 6.2 valence.electron 4.2 <occupied.electrons 1 2.0 2 2.0 2.2 occupied.electrons>The above example is for a virtual atom on the way of carbon and nitrogen atoms. By just controling the above keywords, you can easily generate pseudopotentials and basis functions for virtual atoms. When you use those in OpenMX as input data, no specification by keywords is required. Please make sure that only OpenMX Ver. 3.4 or later accepts the pseudopotentials and the basis functions for the virtual atoms. Also, it is noted that basis functions for the pseudopotential of the virtual atom must be generated for the virtual atom with the same fractional nuclear charge, since the atomic charge density stored in *.pao is used to make the neutral atom potential in OpenMX.