A density functional that accounts for medium-range correlation energies in organic chemistry

It has recently been pointed out that current density functionals are inaccurate for computing stereoelectronic effects and energy differences of isomerization reactions and isodesmic reactions involving alkanes; this has been interpreted as an incorrect prediction of medium-range correlation energies. This letter shows that the recently published M05-2X functional has good accuracy for all three of the recently highlighted problems and should be useful for a wide variety of problems in organic chemistry.