CAP/EOM-CCSD method for the study of potential curves of resonant states

Abstract

The equation-of-motion coupled-cluster (EOM-CC) method along with the complex absorbing potential (CAP) is used for the study of resonance in e(-)-N2 and e(-)-CO. Resonance position and width are studied as a function of bond length. We report the potential curves (PC) of the resonance states.

Structural parameters of the ground states of the quasi‐stable diatomic anions CO−, BF−, and BCl− as obtained by conventional Ab Initio methods

“…The CAP–EOM–CCSD results depend strongly on the basis set size; monitoring the basis set with respect to experiment, at the d‐aug‐cc‐pVDZ+p level (see Ref. for details), E R = 1.30 eV, r e ≈ 1.13Å (see Fig. of Ref.…”

“…The eigenstate of is the Siegert complex energy of the resonance state where E R is the resonance energy and Γ the associated width related to the lifetime of the resonance state τ = ħ /Γ; see Ref. . The physical meaning of the CAP method is to confine the outgoing electron, that is, to avoid the variational collapse to the XY neutral molecule (+ a free e − ), hence transforming the wave function of the resonance state to square‐integrable .…”

“…. The physical meaning of the CAP method is to confine the outgoing electron, that is, to avoid the variational collapse to the XY neutral molecule (+ a free e − ), hence transforming the wave function of the resonance state to square‐integrable . The CAP approach is combined to a standard highly correlated method, for instance coupled‐cluster (CC) including triple excitations, or multireference configuration interaction (MRCI), for the location of resonances ( E R ) and their width (Γ).…”

Projected CAP/SAC‐CI method with smooth Voronoi potential for calculating resonance states

“…So far, the CAP method has been incorporated with multireference configuration interaction calculations, Green's function methods, and coupled cluster and a related orbital theories . Recently, the methodologies based on coupled cluster theory of electron‐attachment (EA) framework have been developed; namely, CAP/symmetry‐adapted cluster‐configuration interaction (SAC‐CI) and CAP/equation‐of‐motion coupled cluster . The further applications of these methods or related theories have been performed for interesting physical processes; for instance, EA, ionization, and interatomic/intermolecular Coulombic decay …”

“…[22,23] Recently, the methodologies based on coupled cluster theory of electron-attachment (EA) framework have been developed; namely, CAP/symmetryadapted cluster-configuration interaction (SAC-CI) [24] and CAP/ equation-of-motion coupled cluster. [25][26][27] The further applications of these methods or related theories have been performed for interesting physical processes; for instance, EA, [28] ionization, and interatomic/intermolecular Coulombic decay. [29] Among these methods, our developments focus on the CAP/SAC-CI method.…”