bas09 input

1. function (a3) : type of function elf/rho
2. filein (a40) : input wfn file
3. iacc free format : accuracy level iacc=0 no approximation in derivative evaluation, 1 and 2 use of a cutoff. 1 is recommanded.
4. external core shell option (a1) : do not merge the external core shell basins (y/n)
5. for each atom bearing a pseudopotential
   • ns1 (free format) : type of the pseudopotential 1 large core, 2 small core
6. attractor search mode (free format) :
   • <0 fast automatic from the current grid, finds only attractors within the box.
   • 0 full automatic, search in the whole molecular space (recommended if symmetry is used).
   • >0 number of expected non protonated valence basins given in input
   • skip if automatic search, for each attractor in input:
     • xp, yp, zp (free format) : cartesian coordinates of the attractor (in a. u.)
     • type, ref_atom

       type: 2 point, 3 circle, 4 sphere. ref_atom is the number of the atom used to define the $C_\infty$ axis in case of circular attractor. For point and sphere attractor put any integer.

     • s_order: synaptic order of the basin.
     • radius: radius of the circle or of the sphere, for point attractors 0.5 can be used safely.
     • basin_name (3a4): atomic symbols used to name the basin.
7. assign grid points (a3) : (y/n)

In output the program writes one file: title_ebas.sbf or title_ras.sbf according to the chosen function to be used by pop09 and one input file for bas09 named temp.bas. The temp.bas file corresponds to the input attractor mode, it can be generated with a different wave function (for example with a smaller basis set) which nevertheless yields the same overall topology and without grid point assignment. In this case it is not necessary to run grid09 before. This procedure is recommended for large systems. Do not forget to update the wfn file name in temp.bas if another wfn file is used.