▁forms ▁clusters ▁with ▁arg on ▁atoms ▁with ▁pe aks ▁at ▁numbers ▁of ▁ 8 , ▁ 1 0 , ▁ 1 6 , ▁ 2 0 , ▁ 2 3 , ▁ 2 5 ▁and ▁ 2 9 , ▁and ▁also ▁at ▁the ▁ icos ah ed ral ▁numbers ▁of ▁ 4 7 , ▁ 5 0 , ▁ 5 7 , ▁ 6 0 , ▁ 6 3 , ▁ 7 7 , ▁ 8 0 , ▁ 1 1 6 ▁and ▁ 1 4 7 ▁arg on ▁atoms . ▁This ▁includes ▁the ▁square ▁anti pr ism ▁( 8 ) ▁and ▁the ▁c apped ▁square ▁anti pr ism ▁( 1 0 ▁atoms ). ▁In ▁Ti + Ar 1 − n ▁the ▁arg on ▁atoms ▁indu ce ▁a ▁mixing ▁of ▁the ▁ground ▁electronic ▁state ▁of ▁ 3 d 2 4 s 1 ▁with ▁ 3 d 3 4 s 0 . ▁ ▁When ▁a ▁pl asma ▁of ▁tit an ium ▁in ▁expand ing ▁arg on ▁gas ▁is ▁made ▁via ▁a ▁las er , ▁clusters ▁from ▁Ti + Ar ▁up ▁to ▁Ti + Ar 5 0 ▁are ▁formed . ▁ ▁But ▁Ti + Ar 6 ▁is ▁much ▁more ▁common ▁than ▁all ▁the ▁others . ▁ ▁In ▁this ▁the ▁six ▁arg on ▁atoms ▁are ▁arranged ▁in ▁an ▁oct ah ed ron ▁shape ▁around ▁the ▁central ▁tit an ium ▁ion . ▁For ▁Ti + Ar 2 ▁D FT ▁calculations ▁predict ▁it ▁is ▁linear , ▁Ti + Ar 3 ▁is ▁not ▁even ▁flat , ▁and ▁has ▁one