This is a Stillinger-Weber (SW) paramaterization for Si with the combined modifications of Balamane et al. (1992) and Hauch et al. (1999). Balamane et al. rescaled the epsilon value from 2.1682 eV to 2.315 eV to obtain the the experimental cohesive energy, E_coh = 4. 63 eV. Hauch et al (1999) doubled the original lambda value from 21.0 to 42.0 to obtain brittle behavior.