center ed ▁integr als ▁van ish . ▁Usually , ▁only ▁the ▁val ence ▁electrons ▁are ▁treated ▁quantum ▁mechan ically ▁while ▁the ▁role ▁of ▁core ▁electrons ▁is ▁to ▁reduce ▁the ▁nuclear ▁charge . ▁Sem i emp ir ical ▁calculations ▁are ▁usually ▁carried ▁out ▁in ▁a ▁minimal ▁basis ▁set . ▁ ▁See ▁also ▁ ▁M ND O ▁ ▁AM 1 ▁ ▁PM 3 ▁ ▁S AM 1 ▁ ▁R M 1 ▁ ▁M OP AC ▁ ▁References ▁ ▁Category : S emi emp ir ical ▁quantum ▁chem istry ▁methods <0x0A> </s> ▁Leg s ▁is ▁a ▁ 1 9 8 3 ▁American ▁made - for - tele vision ▁musical ▁drama ▁film ▁st arring ▁Sh anna ▁Re ed , ▁Deb or ah ▁Ge ff ner , ▁Lawrence ▁L er itz , ▁David ▁Marshall ▁Grant , ▁Ma ure en ▁Te ef y , ▁and ▁G wen ▁Ver don . ▁ ▁It ▁was ▁directed ▁by ▁Jer ro ld ▁Fre ed man ▁and ▁written ▁by ▁Fre ed man ▁and ▁Brian ▁Gar field . ▁▁ ▁The ▁film ▁was ▁ret itled ▁Rock ettes ▁for ▁its ▁UK ▁video ▁release . ▁ ▁This ▁film ▁was ▁G wen ▁Ver don ' s ▁television ▁film ▁debut ▁ ▁and ▁using ▁the ▁tal ents ▁of ▁the ▁ 1 9 8 2 ▁Rock ettes ▁was ▁partially ▁fil med ▁on ▁stage ▁at ▁Radio ▁City ▁Music ▁Hall . ▁ ▁The ▁film ▁had ▁several ▁public ▁screen ings ▁there ▁prior ▁to ▁its ▁television ▁release . ▁ ▁Plot ▁ ▁The ▁film ▁follows ▁three ▁women , ▁Lisa , ▁Terry , ▁and ▁Mel issa , ▁who