( structures ( of ( solids ( , ( molecules ( , ( and atoms ) ) ) ) ) ) )
(ROOT (NP (NP (NNS structures)) (PP (IN of) (NP (NNS solids) (, ,) (NNS molecules) (, ,) (CC and) (NNS atoms)))))
structures of solids, molecules, and atoms
(ROOT (S (NP (NNS Solids)) (VP (VBP are) (VP (VBN categorized) (PP (IN by) (NP (NP (DT the) (NNS forces)) (VP (VBG holding) (NP (NP (DT the) (JJ individual) (NNS atoms)) (, ,) (NP (NNS ions)) (, ,) (CC or) (NP (NNS molecules))) (ADVP (RB together))))))) (. .)))