title: Ground state of naphthyl cation: singlet or triplet?
abstract: We present a benchmark theoretical investigation on the electronic structure and singlet-triplet(S-T) gap of 1- and 2-naphthyl cations using the CCSD(T) method. Our calculations reveal that the ground states of both the naphthyl cations are singlet, contrary to the results obtained by DFT/B3LYP calculations reported in previous theoretical studies. However, the triplet states obtained in the two structural isomers of naphthyl cation are completely different. The triplet state in 1-naphthyl cation is (π,σ) type, whereas in 2-naphthyl cation it is (σ,σ') type. The S-T gaps in naphthyl cations and the relative stability ordering of the singlet and the triplet states are highly sensitive to the basis-set quality as well as level of correlation, and demand for inclusion of perturbative triples in the coupled-cluster ansatz.
authors.affiliation: Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.
authors.forename: Achintya Kumar
authors.initials: AK
authors.lastname: Dutta
authors.affiliation: Department of Chemistry, BITS Pilani, Pilani Campus, India.
authors.forename: Prashant U
authors.initials: PU
authors.lastname: Manohar
authors.affiliation: Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.
authors.forename: Nayana
authors.initials: N
authors.lastname: Vaval
authors.affiliation: Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.
authors.forename: Sourav
authors.initials: S
authors.lastname: Pal