Transition dipole function and radiative lifetimes for the A and C 1Σ+ states of the LiH molecule (original) (raw)
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Journal of Molecular Spectroscopy, 2016
A very accurate dipole moment curve (DMC) for the ground X 1 Σ + electronic state of the 7 LiH molecule is reported. It is calculated with the use of all-particle explicitly correlated Gaussian functions with shifted centers. The DMC-the most accurate to our knowledge-and the corresponding highly accurate potential energy curve are used to calculate the transition energies, the transition dipole moments, and the Einstein coefficients for the rovibrational transitions with ∆J = −1 and ∆v ≤ 5. The importance of the non-adiabatic effects in determining these properties is evaluated using the model of a vibrational R-dependent effective reduced mass in the rovibrational calculations introduced earlier (Diniz et al., Chem. Phys. Lett. 633, 89 (2015)). The results of the present calculations are used to assess the quality of the two complete linelists of 7 LiH available in the literature.
1978
The recently reported (J. Chem. Phys. 66^, 5412 (1977)) hybrid poten tial curves for the X 1 Z + and A 1 Z + states of LiH and the herein reported hybrid potential curve for the B *n state of LiH are combined with the ab initio transition moments of Docken and Hinze (J. Chem. Phys. 57, 4936 (1972)) to calculate radiative transition probabilities between all B X J[ (v 1 < 2) and all X ^ (v" 5 23) and A 1 E + (v" < 26) vibrational levels of 7 LiH. The strongest single emission band found is the B *n (v 1 = 2) *• X 1 Z + (v" = 23) band between the highest "longrange" levels in each potential.
Chemical Physics, 1995
All adiabatic curves of LiH + dissociating into Li (2s, 2p, 3s, 3p, 3d) + H + and Li + + H(1 s, 2s, 2p) are determined by an ab initio approach involving a non-empirical pseudopotential for the Li(1 s 2) core and core valence correlation corrections. The resulting spectroscopic constants and vibrational level spacings of all these states are presented. From ~he usual semiclassical approximations an analysis of the high energy vibrational level spacing is performed allowing for accurate long range extrapolations. For the lowest curves dissociating into Li + + H (I s) and Li (2s) + H + an analysis of the main electronic interactions is carded out from adiabatic model and reveals the importance of the binding charge delocalisation effects versus the polarisation (charge localised) ones. In addition the LiH photoelectron spectrum is calculated. An interesting feature of that spectrum is that both bound-bound and bound-free transitions coexist due to the particular shape of the LiH and LiH + potential energy curves.
Theoretical evaluation of the radiative lifetimes of LiCs and NaCs in the A1Σ+ state
Russian Journal of Physical Chemistry A, 2017
Calculations of the adiabatic potential energy curves and the transition dipole moments between the ground (X 1 Σ +) and the first excited (A 1 Σ +) states have been determined for the LiCs and NaCs molecules. The calculations are performed using an ab initio approach based on non-empirical pseudopotentials for Cs + , Li + and Na + cores, parameterized l-dependent polarization potentials and full configuration interaction calculations. The potential energy curves and the transition dipole moment are used to estimate the radiative lifetimes of the vibrational levels of the A 1 Σ + state using the Franck-Condon (FC) approximation and the approximate sum rule method. The radiative lifetimes associated with the A 1 Σ + state are presented here for the first time. These data can help experimentalists to optimize photoassociative formation of ultracold molecules and their longevity in a trap or in an optical lattice.
Non-Born-Oppenheimer variational calculation of the ground-state vibrational spectrum of LiH[sup +]
The Journal of Chemical Physics, 2006
Very accurate, rigorous, variational, non-Born-Oppenheimer ͑non-BO͒ calculations have been performed for the fully symmetric, bound states of the LiH + ion. These states correspond to the ground and excited vibrational states of LiH + in the ground 2 ⌺ + electronic state. The non-BO wave functions of the states have been expanded in terms of spherical N-particle explicitly correlated Gaussian functions multiplied by even powers of the internuclear distance and 5600 Gaussians were used for each state. The calculations that, to our knowledge, are the most accurate ever performed for a diatomic system with three electrons have yielded six bound states. Average interparticle distances and nucleus-nucleus correlation function plots are presented.
Nonradiative lifetimes for LiH in the A state using adiabatic and diabatic schemes
The Journal of Chemical Physics, 1997
Accurate positions and nonradiative lifetimes of states belonging to the adiabatic A state of LiH are estimated. The results coming from a Golden Rule treatment in the adiabatic scheme present excellent agreement with those obtained through a diabatic close coupling calculation. That confirms the accuracy reached in both approaches and also in the treatment of the diabatic-adiabatic transformation. It involves, in particular, an effective phase control that is needed to properly estimate nonadiabatic couplings. Also, a powerful numerical procedure to obtain energy profiles in the diabatic close coupling frame is described and applied in this work.
Nonadiabatic Calculations of the Dipole Moments of LiH and LiD
Physical Review Letters, 2002
We present very high-accuracy fully nonadiabatic calculated values for the dipole moments for the ground states of LiH and LiD. These results were calculated via numerical differentiation of the energy obtained at different electric field strengths. The values for the energy were obtained from variational optimization with analytical gradients of the wave function expanded in a basis of explicitly correlated floating s-type Gaussian functions. The values obtained for LiH and LiD, 2.3140 and 2.3088 a.u., are nearly identical to those obtained by experiment.
Theoretical study of emission spectra for the isotopic molecule Lithium Li1 6H hydride
A study of the emission spectra of isotopic of LiH molecule for electronic states X1Σ has been carried out. The energies of the vibration levels ν = 0, 1, …, 25 and the values of spectral lines R(J) and P(J) were calculated. A relationship between the spectral lines and the rotational quantum number J = 0, 1, …, 25 was established. It was found that value of R(J) increases with the increase of J, while the value of P(J) decreases with the decrease of J. The Fortrat parabola corresponding to R(J) and P(J) was determined. It was found that the spectral line R(J) increases when the value of m increases, while the value of the spectral line P(J) decreases.
Journal of Molecular Structure: THEOCHEM, 2004
In this work, the inelastic collision of hydroxide of lithium with argon is studied for a fixed experimental value of the LiH bond length 3.0139 bohr using an ab initio energy surface. The potential energy surface (PES) for the LiH(X 1 R + )-Ar( 1 S) Van der Waals system is calculated accurately at the ab initio coupled-cluster [CCSD(T)] with an aug-cc-pVQZ Gaussian basis set for the H and Ar atoms and cc-pVQZ Gaussian basis set for the Li atom. In this calculation, the basis set superposition error (BSSE) was corrected at all geometries with the counterpoise procedure of Boys and Bernadi. The interaction potential has a global minimum at h = 180°and at an equilibrium distance R = 5.30 bohr with a well depth of 525.13 cm À1 . This potential already fitted analytically and expanded in terms of Legendre polynomials is employed to evaluate the state-to-state rotational cross sections over a range of energies up to 6452.584 cm À1 . The calculations of cross sections are done in the close coupling (CC) approach. The features present on low collision energy some resonances and are related to the anisotropic interaction potential. We have compared the cross sections in LiH-Ar at 6452.584 cm À1 with the available experiment one of Wilcomb and Dagdigian and the earlier calculations of Bhattacharyya et al. However, we have found that the results show a good agreement especially for j = 1 ? 0 transition.