Description
SM2 is no longer available and
SM5.2,
SM5.2R,
SM5C, or
SM5CR
should be used instead.
This keyword activates one of the AMSOL models contributed by D.G. Truhlar, C.J. Cramer,
and G.C. Lynch. (See Chapter 15, AMSOL Model Module for a more complete
description of the AMSOL methods and additional dedicated keywords.) By using both the SM2 and
AM1 keywords, the user requests a calculation in aqueous solution by the AM1-SM2 method. While
analogous to the SM1 method in its generality, the SM2 model recognizes the importance of
classifying hydrogen atoms based on the heavy atom to which they are attached and derives that
information from the bond order matrix. As a result, it is considerably more accurate and
consistent than the SM1 approach. The output from such a calculation will include the final
bond order matrix together with the contributions to surface-area-dependent terms from both
heavy-atom surface tensions and attached hydrogen atoms (which do not block the
solvent-accessible-surface-area of the heavy atoms to which they are attached). In SM2 all
accessible-surface-area parameters are independent of chemical environment; thus there is a
unique value for all surface tension parameters for each atom type. Other than including the
SM2 keyword, no modifications need be made to the standard AMPAC
input file.
