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Highlights • Total 34 Λ-S states of AsCl have been studied with the MRCI+Q method. • High-precision spectroscopic results are obtained from the calculated PECs. • The SOC effect makes 34 Λ-S states split into 74 Ω states. • The transition mechanism of a1Δ-X3Σ− and b1Σ+-X3Σ− has been detailedly analyzed. • The accurate lifetimes of a1Δ and b1Σ+ are determined. Abstract A manifold of electronic states for the AsCl radical are accurately characterized at the MRCI+Q level of theory. The potential energy curves (PECs) of 34 Λ-S states, correlated with three dissociation channels, have been constructed, and the spectroscopic constants of the bound Λ-S are determined. The calculated spectroscopic results well reproduce the measurement. A characteristic feature for AsCl is that the open-shell π2 configuration can give rise to the lowest three strongly bound states X3Σ−, a1Δ, and b1Σ+. The spin-orbit (SO) coupling is included using the state interacting method. The calculated SO matrix element indicates that strongly bound a1Δ and b1Σ+ states can be predissociated by A3Π. The SO coupling effect leads to total 74 Ω states. And the calculated energy splitting of X3Σ− amounts to 125 cm−1, in good agreement with the experimental value of 140 ± 8 cm−1. Both a1Δ and b1Σ+ have no SO coupling splitting, and their spectroscopic constants almost keep unchanged. Nevertheless, their dissociation energies D e are strongly decreased due to the avoided crossing. Transition mechanism of several important transitions for AsCl has been clearly expounded. Particularly, the nonzero transition dipole moments (TDMs) of transitions a1Δ-X3Σ− and b1Σ+-X3Σ− are borrowed from spin-allowed Λ-S transitions. Ultimately, the radiative lifetimes of a1Δ and b1Σ+ are determined to be 27.1 ms and 1.1 ms, respectively. [ABSTRACT FROM AUTHOR]

The entire 28 Λ-S electronic states correlated to four dissociation limits of the NTe molecule have been reliably characterized for the first time. The potential energy curves (PECs) and wavefunctions of these Λ-S states are calculated using the multi-reference configuration interaction plus Davidson correction (MRCI+Q) approach, with all-electron correlation-consistent basis sets at quadruple-zeta level. The spectroscopic constants of the bound Λ-S states are determined from the PECs, and the excellent agreement with previous work is derived. By analyzing the dipole moment, the polarity of the ground state for NTe is determined to be N δ− Te δ+ , which is contrary to the case of NO. The spin-orbit coupling (SOC) effect is included when the state interaction method is applied. The SOC effect is found to be substantial for the NTe molecule, which makes the lowest 10 Λ-S states split into 30 Ω states. The X 2 Π states split into two Ω states including X 2 Π 1/2 (X 1 1/2) and X 2 Π 3/2 (X 2 3/2), and the corresponding SOC splitting is computed to be 1975 cm −1 (0.245 eV). Analysis of Λ-S compositions for the Ω-state wavefunction indicates the strong interaction among the Λ-S states. Additionally, the transition properties of the Ω-state transitions 1/2(2)-X 1 1/2, 1/2(4)-X 1 1/2, 3/2(10)-X 2 3/2, and 5/2(1)-X 2 3/2 were predicted. These transitions are all mainly from the spin-forbidden Λ-S transitions, but their transition dipole moments arise from those of the spin-allowed Λ-S transitions via the SOC effect. Accordingly, these transitions have quite long radiative lifetimes that are at the microsecond (ms) level. [ABSTRACT FROM AUTHOR]

The entire 23 Λ-S states of the PCl + molecule have been studied by using the high-level relativistic MRCI+Q method with full-electron aug-cc-pCVQZ-DK basis set. The potential energy curves(PECs) and wavefunctions of the states have been calculated. From the PECs, the spectroscopic constants of the bound states are also determined, and the good agreements could be found with the experiments. The high density region of states exhibits many PECs' crossings, which lead to complicated interaction of the states. Here, the interactions arising from the dipolar interaction and spin-orbit coupling (SOC) effect have been discussed in detail. Under the influence of the SOC effect, the A 2 Π state is perturbed by the 1 4 Σ - state. Considering the SOC effect, total 45 Ω states are generated from the original 23 Λ-S states. The transition properties are also predicted, including the transition dipole moments, Franck-Condon factors, and radiative lifetimes. The lifetimes of the transitions A 2 Π 1/2 -X 2 Π 1/2 and A 2 Π 3/2 -X 2 Π 3/2 are determined to be 478.9 ns and 487.0 ns( v' =0), respectively. [ABSTRACT FROM AUTHOR]

Total 34 Λ-S states of the PCl molecule have been studied by using the multi-reference configuration interaction plus the Davidson correction (MRCI+Q) method with the correlation consistent quadruple-zeta quality basis set. These states are correlated to three dissociation limits P( 4 S u )+Cl( 2 P u ), P( 2 D u )+Cl( 2 P u ), and P( 2 P u )+Cl( 2 P u ), respectively. The potential energy curves (PECs) of the Λ-S states have been calculated, from which the spectroscopic constants of the bound states are determined. The calculated spectroscopic results well reproduce the available measurements. The spin–orbit matrix elements between the Λ-S states have been calculated, which indicate that the perturbations exist in the interacting system 1 1 Π−2 3 Π and 1 1 Π−2 3 Σ − . And the excited a 1 Δ, b 1 Σ + , 2 1 Σ + states could be predissociated induced by the spin–orbit coupling (SOC) effect. The SOC calculation on the PCl molecule has been performed with the state interaction method. This is the first time that the SOC effect of the PCl has been studied theoretically. The SOC effect leads to the 34 Λ-S states split into the 74 Ω states. The ground state X 3 Σ − splits into the X 3 Σ 0 − + (X 1 0 + ) and X 3 Σ 1 − (X 2 1) states. For the zero-field splitting of the X 3 Σ − state, the spin–orbit contribution of 6 cm −1 is much larger than spin-spin contribution of 0.32 cm −1 . Under the influence of the SOC effect, the spectroscopic results of the a 1 Δ and b 1 Σ + states have very small changes, but the dissociation energies strongly decrease. The transition properties of PCl are also predicted, including the E 1, M 1, and E 2 transition moments, the Franck–Condon factors, the transition probabilities, and the radiative lifetimes. For the transitions from a 1 Δ-X 3 Σ − and b 1 Σ + −X 3 Σ − , the transition probabilities are in order of A E 1 > A M 1 ≫ A E 2 . The lifetimes for the b 1 Σ + ( v׳ =0) state are 4.87ms ( E 1) and 4.57 ms ( E 1+ M 1), in good agreement with the available experimental result of 4.9±0.8 ms. [ABSTRACT FROM AUTHOR]

The potential energy curves (PECs) of the 22 Λ–S states of the phosphorus monoiodide (PI) molecule have been calculated at the level of MRCI+Q method with correlation-consistent quadruple-ζ quality basis set. The spectroscopic constants of the bound states are determined, which well reproduce the available measurements. The metastable a 1 Δ state has been reported for the first time, which lies between the X 3 Σ − and b 1 Σ + states and have much deeper well than the ground state. The R -dependent spin–orbit (SO) matrix elements are calculated with the full-electron Breit–Pauli operator. Based on the SO matrix elements, the perturbations that the 2 3 Π state may suffer from are analyzed in detail. The SOC effect makes the original Λ–S states split into 51 Ω states. In the zero-field splitting of the ground state X 3 Σ − , the spin–spin coupling contribution (2.23 cm −1 ) is found to be much smaller compared to the spin–orbit coupling contribution (50 cm −1 ). The avoided crossings between the Ω states lead to much shallower potential wells and the change of dissociation relationships of the states. The Ω-state wavefunctions are analyzed depending on their Λ–S compositions, showing the strong interactions among several quasidegenerate Λ–S states of the same total SO symmetry. The transition properties including electric dipole ( E 1), magnetic dipole ( M 1), and electric quadrupole ( E 2) transition moments ( TM s), the Franck–Condon factors, the transition probabilities and the radiative lifetimes are computed for the transitions between Ω components of a 1 Δ and b 1 Σ + states and ground state. The transition probabilities induced by the E 1, E 2, and M 1 transitions are evaluated. The E 2 makes little effect on transition probabilities. In contrast, the E 1 transition makes the main contribution to the transition probability and the M 1 transition also brings the influence that cannot be neglected. Finally, the radiative lifetimes are determined with the transition moments including E 1 and M 1. The lifetime of transition (2)0 + –X 1 0 + is evaluated at the level of millisecond, much smaller than that of the transition (2)0 + –X 2 1. [ABSTRACT FROM AUTHOR]

Abstract: The entire 12 Λ–S states of CCl+ correlated to ground state atom C+ and Cl are calculated at scalar relativistic MRCI+Q/AV5Z level of theory. Spin–orbit interaction causes the 12 Λ–S states to split into 23 Ω states. The potential energy curves (PECs) of Λ–S and Ω states are depicted with the aid of the avoided crossing rule between the same symmetry. This is the first time that spin–orbit coupling (SOC) calculation has been carried out on CCl+. The spin–orbit coupling effect, leading to many avoided crossings, is found to be substantial for CCl+. The spectroscopic constants of the bound Λ–S and Ω states are determined, where a better agreement with experimental data is found. The predissociations for a3Π and A1Π induced by SOC are analyzed. Moreover, the transition properties, including transition dipole moments and Franck–Condon factors, are derived. Subsequently, the radiative lifetimes of transition a3Π0+–X1Σ+ 0+ and a3Π1–X1Σ+ 0+ are calculated. [Copyright &y& Elsevier]

• Total 34 Λ-S states of SbI are accurately characterized at the MRCI+Q level. • The SOC effect makes 34 Λ-S states split into 74 Ω states. • Transition mechanisms of a1Δ-X3Σ− and b1Σ+-X3Σ− are illustrated. • The SOC effect is indispensible for accurate spectroscopic determinations of SbI. In this work, all-electron ab initio calculations on the SbI molecule have been carried out with the multi-reference configuration interaction plus the Davidson correction (MRCI+Q) method. In the calculations, total 34 Λ-S states have been obtained for the first time. From calculated PECs, the derived spectroscopic constants well agree with available experimental values. It should be mentioned that A3Π is typically repulsive, which much differs from the cases of lighter analogs SbX(X=F, Cl, and Br). The molecule is expected to possess a strong spin-orbit coupling effect because both Sb and I atoms have a large atomic number (Z). Therefore, this effect is included by using the state interaction method. As a result, there are 74 Ω states generated from Λ-S states. For X3Σ−, the determined energy splitting of 980 cm−1 is in good agreement with the measured value of 965 cm−1. The adiabatic excitation energy T e of b1Σ+ is greatly improved after considering the SOC effect. Transition properties of SbI are evaluated. The obtained results demonstrate that SOC effects have a great impact on the transitions a1Δ-X3Σ− and b1Σ+-X3Σ−. Both transitions borrow transition dipole moments (TDMs) from spin-allowed Λ-S transitions. The radiative lifetimes of a1Δ and b1Σ+ are determined to be 2.28 ms and 96.84 μs, respectively. [ABSTRACT FROM AUTHOR]

High-level ab initio calculations on the ground and the excited states of the SrH molecule have been carried out utilizing the multi-reference configuration interaction method plus Davidson correction (MRCI+Q) method, with small-core relativistic effective core potentials together with the corresponding correlation consistent polarized valence basis sets. The potential energy curves (PECs) of the 16 Λ–S states have been obtained with the aid of the avoided crossing rule between electronic states of the same symmetry. The spectroscopic constants of the bound states were calculated, most of which have been reported for the first time, with those pertaining to the X 2 Σ + , A 2 П, B 2 Σ + , and A′ 2 Δ states being in line with the available experimental and theoretical values. The calculated spin–orbit matrix element indicates a strong interaction between the X 2 Σ + and A 2 П states in the Franck–Condon region. The spin–orbit coupling (SOC) splits the lowest strongly bound X 2 Σ + , A 2 П, A′ 2 Δ, B 2 Σ + , and D 2 Σ + states into 9 Ω states. For the D 2 Σ + state, the SOC shifts the potential-well minimum to higher energy and shortens the bond length. The transition properties of the bound Λ–S states were predicated, including the transition dipole moments (TDMs), the Franck–Condon factors, and the radiative lifetimes. The lifetimes were calculated to be 34.2 ns ( v ′=0) and 55.0 ns ( v ′=0) for A 2 П and B 2 Σ + , in good agreement with the experimental results of 33.8±1.9 ns and 48.4±2.0 ns. [ABSTRACT FROM AUTHOR]

Germanium monohydride (GeH), an important radical for the growth of semiconductor germanium film, has received much attention. However, the electronic structure and spectroscopic properties of low-lying excited states of the radical have not been well understood, especially the coupling between different electronic states. In this work, eight Λ–S valence states and four low-lying Λ–S Rydberg states correlated to the four lowest dissociation limits of GeH are investigated by employing the multireference configuration interaction method. With the inclusion of spin–orbit coupling effect, there are 24 Ω states generated from 12 Λ–S states. On the basis of computed potential energy curves of the Λ–S and Ω states, the spectroscopic parameters of bound states are evaluated, which demonstrate that the first Rydberg state 3 2 Σ + located at 5.12 eV is exactly the B 2 Σ + state tentatively assigned by experiment. With the help of the calculated spin–orbit matrix elements, the predissociation mechanism of A 2 Δ state is investigated, which may interpret the fact that ν′>2 vibrational levels of A 2 Δ state are difficult to be detected in experiment. Finally, the transition dipole moments and the radiative lifetimes of several vibrational levels of A 2 Δ and a 4 Σ − states are calculated. [ABSTRACT FROM AUTHOR]

• Total 34 Λ-S states of SbBr are accurately characterized at the MRCI+Q level. • The SOC effect makes 34 Λ-S states split into 74 Ω states. • Transition mechanisms of a1Δ-X3Σ− and b1Σ+-X3Σ− are illustrated. • The SOC effect is indispensible for accurate spectroscopic determinations of SbBr. In this work, we performed spin-orbit coupling (SOC) included MRCI+Q calculation on electronic states of SbBr. The SOC effect is treated by using the state interaction method in combination with the Breit-Pauli operator. Molecular orbitals are constructed with all-electron aug-cc-pwCVQZ-DK basis sets. Without SOC, total 34 Λ-S states of SbBr are obtained. It is found that the lowest three Λ-S states X3Σ−, a1Δ, and b1Σ+ are characterized by a common electron configuration (π2). All of them possess an especially deep potential well. Predissociations of a1Δ and b1Σ+ are illuminated with the aid of SO matrix elements. Under the influence of SOC, total 74 Ω states arise from Λ-S states. The energy splitting of X3Σ− is calculated to be 868 cm−1, which well reproduces the measurement of 873 cm−1. Particularly, SOC effects significantly improve the excitation energy (T e) of b1Σ+. The deviation is decreased from 1378 cm−1 to 233 cm−1. In addition, the SOC effect has a great effect on transition properties of SbBr. This effect is responsible for the phosphorescence of transitions a1Δ-X3Σ− and b1Σ+-X3Σ−, and the corresponding transition mechanism is elucidated. Finally, radiative lifetimes of a1Δ and b1Σ+ are determined at a millisecond level. [ABSTRACT FROM AUTHOR]

• Total 34 Λ-S states of SbCl are accurately characterized at the MRCI+Q level. • The SOC effect makes 34 Λ-S states split into 74 Ω states. • Transition mechanisms of a1Δ-X3Σ- and b1Σ+-X3Σ- are illustrated. • The SOC effect is indispensible for accurate spectroscopic determinations of SbCl. In this paper, all-electron relativistic MRCI+Q calculation has been carried out on electronic and spectroscopic properties of SbCl. In present calculation, total 34 Λ-S and 74 Ω have been reliably characterized for the first time. The lowest three Λ-S states X3Σ−, a1Δ, and b1Σ+ possess a rather deep potential well, and resulting spectroscopic constants are consistent with experiments. The spin-orbit coupling (SOC) effect is considered with the state interaction method, and then the accuracy of computation is further improved. The SOC induced predissociations of a1Δ and b1Σ+ are illuminated by using spin-orbit matrix elements. It is found that the SOC effect is substantial for SbCl. The effect gives rise to a more complicated structure of electronic states. Transition properties of SbCl are estimated. R -dependent transition dipole moments (TDMs) are obtained at the MRCI level. Both a1Δ-X3Σ− and b1Σ+-X3Σ− borrow TDMs from spin-allowed Λ-S transitions via SOC. The lifetimes of a1Δ and b1Σ+ are determined at a millisecond (ms) level. [ABSTRACT FROM AUTHOR]