. ▁they ▁can ▁be ▁understood ▁as ▁approximately ▁local ▁and ▁hence ▁transfer able ▁properties . ▁ ▁Det erm ination ▁ ▁The ▁mole cular ▁geometry ▁can ▁be ▁determined ▁by ▁various ▁spect ro scop ic ▁methods ▁and ▁diff raction ▁methods . ▁IR , ▁mic row ave ▁and ▁Ram an ▁spect ro sc opy ▁can ▁give ▁information ▁about ▁the ▁mole c ule ▁geometry ▁from ▁the ▁details ▁of ▁the ▁v ibr ational ▁and ▁rot ational ▁abs orb ance ▁detected ▁by ▁these ▁techniques . ▁X - ray ▁cry stal log raph y , ▁neut ron ▁diff raction ▁and ▁electron ▁diff raction ▁can ▁give ▁mole cular ▁structure ▁for ▁cry st all ine ▁sol ids ▁based ▁on ▁the ▁distance ▁between ▁nuc lei ▁and ▁concentration ▁of ▁electron ▁density . ▁Gas ▁electron ▁diff raction ▁can ▁be ▁used ▁for ▁small ▁mole cules ▁in ▁the ▁gas ▁phase . ▁N MR ▁and ▁F RE T ▁methods ▁can ▁be ▁used ▁to ▁determine ▁complement ary ▁information ▁including ▁relative ▁distances , ▁di hed ral ▁angles , ▁ ▁angles , ▁and ▁connect ivity . ▁ ▁M ole cular ▁geomet ries ▁are ▁best ▁determined ▁at ▁low ▁temperature ▁because ▁at ▁higher ▁temper atures ▁the ▁mole cular ▁structure ▁is ▁aver aged ▁over ▁more ▁accessible ▁geomet ries ▁( see ▁next ▁section ). ▁Lar ger ▁mole cules ▁often ▁exist ▁in ▁multiple ▁stable ▁geomet ries ▁( con form ational ▁is omer ism ) ▁that ▁are ▁close ▁in ▁energy ▁on ▁the ▁potential ▁energy ▁surface . ▁ ▁Ge omet ries ▁can ▁also ▁be ▁computed ▁by ▁ab ▁init io ▁quantum ▁chem istry ▁methods ▁to ▁high ▁accuracy . ▁ ▁The