Specifies that the size-modified PBE should be solved as described by Chu V, et al Biophys J, 93(9):3202-9, 2007 (doi:10.1529/biophysj.106.099168). The syntax is

   smpbe vol { spacing } size { num }

The parameter spacing is a floating point number in Ångstroms used specify the lattice spacing such that each lattice site has a volume equal to spacing³. The parameter num controls the relative size of the ions (in Ångstroms) such that each lattice site can contain a single ion of volume spacing³ or num ions of volume spacing³/size.

See also: lpbe, npbe, lrpbe, nrpbe