▁Wa als ▁mole cules ▁held ▁together ▁very ▁weak ly ▁by ▁London ▁disp ersion ▁forces . ▁I onic ▁mole cules ▁can ▁be ▁bound ▁by ▁charge ▁induced ▁di pole ▁interactions . ▁With ▁gold ▁atoms ▁there ▁can ▁be ▁some ▁c oval ent ▁interaction . ▁Several ▁bor on - arg on ▁b onds ▁with ▁significant ▁c oval ent ▁interactions ▁have ▁been ▁also ▁reported . ▁Ex perimental ▁methods ▁used ▁to ▁study ▁arg on ▁comp ounds ▁have ▁included ▁in ert ▁gas ▁matrices , ▁inf ra red ▁spect ro sc opy ▁to ▁study ▁stretch ing ▁and ▁b ending ▁movements , ▁mic row ave ▁spect ro sc opy ▁and ▁far ▁inf ra red ▁to ▁study ▁rotation , ▁and ▁also ▁visible ▁and ▁ult rav io let ▁spect ro sc opy ▁to ▁study ▁different ▁electronic ▁configurations ▁including ▁exc im ers . ▁Mass ▁spect ro sc opy ▁is ▁used ▁to ▁study ▁ ions . ▁Comput ation ▁methods ▁have ▁been ▁used ▁to ▁theoret ically ▁compute ▁mole c ule ▁parameters , ▁and ▁predict ▁new ▁stable ▁mole cules . ▁Comput ational ▁ab ▁init io ▁methods ▁used ▁have ▁included ▁CC SD ( T ), ▁MP 2 ▁( M ø ll er – P less et ▁perturb ation ▁theory ▁of ▁the ▁second ▁order ), ▁C IS ▁and ▁C IS D . ▁For ▁heavy ▁atoms , ▁effective ▁core ▁potential s ▁are ▁used ▁to ▁model ▁the ▁inner ▁electrons , ▁so ▁that ▁their ▁contributions ▁do ▁not ▁have ▁to ▁be ▁individually ▁computed . ▁More ▁powerful ▁computers ▁since ▁the ▁ 1 9 9 0 s ▁have ▁made ▁this ▁kind ▁of ▁in ▁sil ico ▁study