Non-bonding interactions are excluded for bonded atoms 1-3 and electrostatic interactions are modified by the constant factor of 0.83 for bonded atoms 1-4. The van der Waals interactions for bonded atoms 1-4 are divided by 2.0 (scnb=2.0). The cut-off for van der Waals and electrostatic interactions is set to 50 Å to avoid instabilities in large molecules.