Nitric acid (NA) has previously been shown to affect
atmospheric
new particle formation; however, its role still remains highly uncertain.
Through the employment of state-of-the-art quantum chemical methods,
we study the (acid)
1–2
(base)
1–2
and (acid)
3
(base)
2
clusters containing at
least one nitric acid (NA) and sulfuric acid (SA) or methanesulfonic
acid (MSA) with bases ammonia (A), methylamine (MA), dimethylamine
(DMA), trimethylamine (TMA), and ethylenediamine (EDA). The initial
cluster configurations are generated using the ABCluster program.
PM7 and ωB97X-D/6-31++G(d,p) calculations are used to reduce
the number of relevant configurations. The thermochemical parameters
are calculated at the ωB97X-D/6-31++G(d,p) level of theory with
the quasi-harmonic approximation, and the final single-point energies
are calculated with high-level DLPNO–CCSD(T
0
)/aug-cc-pVTZ
calculations. The enhancing effect from the presence of nitric acid
on cluster formation is studied using the calculated thermochemical
data and cluster dynamics simulations. We find that when NA is in
excess compared with the other acids, it has a substantial enhancing
effect on the cluster formation potential.