PM6-DH2X

In addition to the PM6-DH2 corrections, PM6-DH2X includes corrections to the halogen-oxygen and halogen-nitrogen interactions, as described in J. Rezác and P. Hobza, "A halogen-bonding correction to the semiempirical PM6 method" Chem. Phys. Lett., 506 286-289 (2011)