Environmental Pollutants (n_yo_x) _n Clusters With Theoretical Research

Nitrogen oxides are important contamination in the atmosphere, and study on their configurations andproperties is constantly concerned by people. This article carried out quantum chemical calculations for themolecular configurations and thermochemistry properties of (N_yO_x)_n clusters by using the B3LYP methodfrom Density Functional Theory, with doubleξpolarization of all electrons and basis set of dispersefunction. These calculations are involved with neutral molecules, cations and anions of (NO)_x,N(NO)_xå'Œ(N₂O)_x family, providing a number of molecular structures. From the outcome of calculations, moststructures are similar to intergradations, and their families tend to be dispersed. Certain "chemical bonds"have the bond length exceeding the range of theoretical bond length dramatically, but these structures don'thave feint frequency. They are relatively stable. This kind of effect between real chemical bond andmolecular force (van der Waals force) is a complicated weak effect. It has become another hot topic forresearches around the world. Annular configuration is generally more convergent than otherconfigurations: its bond length is within the theoretical range. As the X value in the molecular formulaincreases, stable molecular structure tends to be annular, and annular structure tends to be stable.Therefore, most of the large molecular structures of nitrogen oxides are annular. Linear structures areunstable, for these molecules have relatively more feint frequencies.For bond length, it basically follows one rule: N-N bond length in anionic structure is shorter thanN-N bond length in neutral molecule structure, but N-O bond length is longer than that in neutral molecularstructure. Cationic structures have just the opposite circumstance to anionic ones. N-N bond length islonger than that in neutral molecules: N-O bond length is shorter than that in neutral molecules. From theenergy point of view, for almost all structures, there is little difference between their energy and themultiple or sum of energy of their corresponding single units. This special phenomenon implies that no newchemical bond is generated in the structure. Therefore, it is questioned that whether (N_yO_x)_n exists as a newform of substance. Meanwhile, this phenomenon can better prove the existence of the complicated weekeffect mentioned above. This article also provides decompounded energy of certain structures.