The　interactions　between　NOx,　N　and　O　atoms,　and　aluminum　(Al)　surfaces　including　crystal　planes　and　nanoparticles　(ANPs)　are　systematically　investigated　by　using　density　functional　theory　(DFT)　calculations,　canonical　Monte　Carlo　(CMC)　simulations,　and　reactive　molecular　dynamics　(RMD)　simulations.　NOxhas　two　adsorption　states　(molecular　and　dissociated)　on　the　Al　surfaces,　which　are　separated　by　a　low　energy　barrier.　The　adsorption　of　NOxin　either　state　does　not　favor　Al　nanoparticles　(ANPs),　opposite　to　its　behavior　on　transition　metals.　In　addition,　NOxdoes　not　show　preference　toward　smaller　ANPs　or　their　vertices　or　edges;　instead,　it　prefers　threefold　sites　that　resemble　the　fcc　or　hcp　sites　on　a　(111)　surface.　The　big　deformation　energy　of　ANPs　is　found　to　be　the　reason.　The　N∗　adatoms　are　most　stable　at　the　tetrahedron　interstitial　sites　between　the　surface　and　the　first　sublayer,　where　an　aluminum　nitride　(AlN)-like　structure　is　formed.　Similar　to　O∗　adatoms　on　Al,　the　isotropic　attraction　between　N∗　adatoms　has　a　significant　influence　on　their　diffusion,　both　in-plane　and　in　cross-layer.　Besides,　the　attraction　within　a　N-O　pair　as　the　first　nearest　neighbors　(1NN)　is　roughly　twice　that　of　their　respective　attraction　(about　0.1　eV/O-O　or　N-N).　However,　RMD　simulations　ignore　the　attraction　among　the　N∗　adatoms　as　well　as　between　the　N∗　and　O∗　adatoms,　though　O-O　attractions　are　somehow　incorporated.　CMC　simulations　prove　that　the　attraction　still　governs　the　configuration　of　the　adatoms　at　600　K　with　all　adatoms　congregating　into　a　single　polygonal　island,　and　it　is　still　influential　even　when　reaching　1500　K.　In　addition,　the　fragmented　products　(AlxNy)　of　Al　combustion　in　NOxaccording　to　DFT　feature　the　tetra-coordinated　Al　centered　inside　the　tetrahedron　of　four　N　atoms,　different　from　the　pyramidal　unit　structure　with　Al　as　the　vertex　by　RMD　simulations.　Our　results　demonstrate　that　the　unusual　behaviors　of　NOxincluding　the　dissociated　atoms　on　Al　are　caused　by　both　the　softness　(low　Young＇s　modulus)　of　Al　and　the　attractions　among　adsorbates,　which　have　important　implications　for　understanding　the　behaviors　of　gas　molecules　on　main　group　metals　in　general.　©　2022　American　Chemical　Society.　All　rights　reserved.