Elastic scattering of two ground-state N atoms

An interaction potential for an N$_{2}$(X$^{1}Sigma_{rmg}^{ + })$ molecule is constructed by using the highly accuratevalence internally contracted multireference configurationinteraction method and the largest basis set, aug-cc-pV6Z, in thevalence range. The potential is used to investigate the elasticscattering of two N atoms at energies from 1.0$times $10$^{ - 11}$to $1.0times 10^{ - 4}$ a.u. The derived total elastic crosssections are very large and almost constant at ultralowtemperatures, and the shape of total elastic cross section curve ismainly dominated by the $s$-partial wave at very low collisionenergies. Three shape resonances are found in the total elasticcross sections. Concretely, the first one is very sharp and strong.It results from the $g$-partial-wave contribution and the resonantenergy is $3.645times 10^{ - 6}$ a.u. The second one is contributedby the $h$-partial wave and the resonant energy is $1.752times 10^{- 5}$ a.u. This resonance is broadened by those from the $d$- and$f$-partial waves. The third one comes from the $l = 6$ partial wavecontribution and the resonant energy is $3.522times 10^{ - 5}$ a.u.This resonance is broadened by those from the $g$- and $h$-partialwaves. The N$_{2}$(X$^{1}Sigma _{rm g}^{ + })$ molecularparameters, which are determined at the current theoretical level,achieve very high accuracy due to the employment of the largestcorrelation-consistent basis set in the valence range.