Computational Chemistry Wiki

MIDI! (or MIDIX) is a small basis set designed to provide good geometries and partial charges, with emphasis of biomolecules functional groups. Includes d polarization functions for atoms excepting H and C. It is a modification of the original MIDI of Huzinaga. It provides better geometries than the much bigger 6-31G*. MIDIY is an extension that includes p polarization on H. Also MIDIX+ and MIDIY+ were developed


H : (3s) -> [2s]
C : (6s,3p) -> [3s,2p]
N - F : (6s,3p,1d) -> [3s,2p,1d]
P - Cl: (9s,6p,1d) -> [4s,3p,1d]
Si : (9s,6p,1d) -> [4s,3p,1d]
Br : (15s,9p,4d) -> [5s,4p,2d]
I : (18s,12p,7d) ->[6s,5p,3d]


  • Easton, Giesen, Welch Cramer, Truhlar Theor. Chem. Acta 1996, 93, 281
  • Li, Cramer, Truhlar Theor. Chem. Acta 1998, 99, 192
  • Lynch, Truhlar Theor. Chem. Acta , 111, 335
  • Basis set exchange (BSE):
  • Cramer, C. J. (2004) Essentials of Computational Chemistry, 2nd Ed. John Wiley & Sons.