I notice that in Charmm parameter files some atoms have two sets of vdw parameters - one for the 'normal' vdw interaction and the other for 1-4 vdw interaction. For example:
C 0.000000 -0.110000 2.000000 ! ALLOW PEP POL ARO
! NMA pure solvent, adm jr., 3/3/93
CT1 0.000000 -0.020000 2.275000 0.000000 -0.010000 1.900000 ! ALLOW ALI
! isobutane pure solvent properties, adm jr, 2/3/92
My question is this: if an atom does not contain the second set of parameters (such as C as shown above), does Charmm still include the 1-4 interactions for an atom pair that contain atom C?