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Examines the stationary point of abstraction reaction at the fully optimized reaction space (FORS) level. Single-point calculations by unrestricted Moller-Plesset fourth order perturbation theory; Values of the activation energies.

Abstract: Accurate double ionization energies (DIEs) for low-lying doubly charged states of HCl, HBr, Cl2 and Br2 were calculated using non-relativistic CASSCF/MRCI level of theory with the aug-cc-pVQZ basis set. The results are in excellent agreement with experimental data, presenting absolute average deviations lower than 0.3eV. Some DIEs not previously assigned or well characterized are discussed. Further improvements can be reached by including relativistic effects. [Copyright &y& Elsevier]

Abstract: Geometries, energies, frequencies, and rate constants of the reaction F (2P)+C2H6 →C2H5 +HF were computed using the MP2 and CCSD(T) approaches, correlation-consistent basis sets, and an extrapolation scheme to assess the complete basis set (CBS) limit energies. Values of the enthalpy of reaction at 0K calculated with the CCSD(T)/cc-pVQZ method and extrapolated to the CBS limit are equal to −35.2 and −36.7kcal/mol, respectively (Exp. −35.3±0.5kcal/mol). Rate constants calculated with the zero-order interpolated variational transition state (IVTST-0) method are in good agreement with experiment. [Copyright &y& Elsevier]

Abstract: The effect of constraints on the initial steps of the incorporation of nitrogen on silicon has been assessed by calculations with the [Si9H12 +N] model cluster using density functional theory with the hybrid functional B3LYP, and two basis sets that differ significantly in size. The relative stability of the various stationary points is dependent on the type of constraints imposed on the cluster. Constrained calculations have predicted the structure with the nitrogen symmetrically bonded to the dimer silicons as the global minimum, however, if no constraint is imposed and the whole cluster is optimized, as done in this work, a structure with the nitrogen inserted between the dimer and the first layer and bonded to three silicon atoms is predicted to be the most stable one by about 17kcal/mol by either the doublet or quartet route. The whole process is very exothermic and reaction barriers in the intermediate steps are easily overcome. Calculations with the smaller basis do not essentially change the major conclusion about the relative stability of the various stationary points. The most stable structure and frequency calculations are consistent with a planar NSi3 moiety and its asymmetrical stretching frequency. [Copyright &y& Elsevier]

Abstract: The CH4 +F(2P)→CH3 +HF abstraction reaction was investigated using the BH&HLYP, MP2, and CCSD(T) approaches, and two series of correlation consistent basis sets. At the CCSD(T)/cc-pVTZ level, the classical barrier height (ΔV #), and the vibrationally adiabatic ground-state barrier height () are equal to 1.8 and 0.5kcal/mol, respectively. CCSD(T)/cc-pVQZ calculations give a value for the enthalpy of reaction at 0K () of −31.5kcal/mol (Expt. −32.1kcal/mol). Rate constants calculated with the zero-order interpolated variational transition state (IVTST-0) method are in agreement with experiment. The activation energy computed as local two-points slopes of Arrhenius plots in the temperature range of 200–400K, equal to 0.59kcal/mol, is also in good agreement with experiment (0.53kcal/mol). [Copyright &y& Elsevier]

Abstract: Kinetic isotope effects (KIE) for hydrogen abstraction from CH4, CD4, and 13CH4 by fluorine was studied by the variational transition state theory with multidimensional tunneling contributions (VTST/MT). A low-level potential energy surface is obtained with the AM1SRP method. High-level energies, geometries and frequencies of the reactants, transition state, and products were computed using MP2 and CCSD(T) methods. Using the CVT/μOMT method, the kH/kD kinetic isotope effect value is 1.52 (298K), in excellent agreement with experimental values (1.4–1.5). All computed values of k12C/k13C KIE over a large range of temperatures (200–2000K) show normal values (KIE>1). [Copyright &y& Elsevier]

Electronic energies, geometries, and harmonic vibration frequencies for the reactants, products, and transition state for the Cl(3P)+C2H6→C2H5+HCl abstraction reaction were evaluated at the HF and MP2 levels using several correlation consistent polarized-valence basis sets. Single-point calculations at PMP2, MP4, QCISD(T), and CCSD(T) levels were also carried out. The values of the forward activation energies obtained at the MP4/cc-pVTZ, QCISD(T)/cc-pVTZ, and CCSD(T)/cc-pVTZ levels using the MP2/cc-pVTZ structures are equal to −0.1, −0.4, and −0.3 kcal/mol, respectively. The experimental value is equal to 0.3±0.2 kcal/mol. We found that the MP2/aug-cc-pVTZ adiabatic vibration energy for the reaction (−2.4 kcal/mol) agrees well with the experimental value −(2.2–2.6) kcal/mol. Rate constants calculated with the zeroth-order interpolated variational transition state (IVTST-0) method are in good agreement with experiment. In general, the theoretical rate constants differ from experiment by, at most, a factor of 2.6. [Copyright &y& Elsevier]

Accurate optimized equilibrium geometries, harmonic frequencies and rotational constants of the gauche conform (C2 symmetry) of hydrazine (N2H4) have been calculated employing a large series of basis sets and several ab initio methods. Our best estimate computed equilibrium geometries are rNN=1.434 A˚, rNHi=1.013 A˚, rNHo=1.010 A˚, θNNHi=111.3°, θNNHo=106.8° and θHiNNHo=89.7°. These predictions were used as reference in the analysis of the experimental and theoretical data, and we expected that the present results could guide future investigations in this direction. [Copyright &y& Elsevier]

Abstract: A theoretical study of the electronic structure of zinc phthalocyanine (ZnPc) ground state was carried out using ab initio and DFT methods. The DFT and MP2 methods indicated a D 4h structure, while HF predicted a slightly distorted geometry. The DFT infrared spectra with the corrected wave number values presented good agreement with experiment. The solvation influence on the geometrical parameters, atomic charges and HOMO–LUMO energies was estimated with the use of PCM method and DMSO as solvent. The presence of solvent did not alter these parameters, but affected the orbital energies. The aggregation phenomena were studied with ZnPc dimer and trimer structures. The previously unknown ZnPc dimer infrared spectrum was obtained and compared to the one from monomer. The dimer and trimer stabilization energies are indicative that the formation of stacked structures with several ZnPc is a favorable process. [Copyright &y& Elsevier]

Abstract: Barrier heights, structures, reaction energies, and rate constants are calculated with the DFT, MP2, and CCSD(T) methods for the first two channels of the H+CH3OH reactions. The best estimate results based on CCSD(T) calculations give reaction enthalpies () for the first (−8.4kcal/mol) and second (0.8kcal/mol) reactive channels, which are comparable to the experimental values, −8.8±0.9 and −0.3±0.9kcal/mol, respectively. Rate constants and activation energies calculated with the IVTST-0 method using CCSD(T)/cc-pVTZ geometries and frequencies are also in excellent agreement with experiment data. [Copyright &y& Elsevier]

Abstract: Geometries, frequencies, energies, and rate constants of the reaction N(4S)+CH4 →NH+CH3 were computed using coupled-cluster theory, correlation-consistent basis sets, and extrapolations schemes to assess the complete basis set limit energies. Our best calculation gives a classical barrier height and reaction energy of 32.9 and 29.3kcal/mol, respectively, and 24.6kcal/mol for the reaction enthalpy (. Thermal (200–2000K) rate constants were calculated with the canonical variational transition state theory, and indicate a very slow reaction when compared with the ones with N(2D) and N(2P). Using the CVT/μOMT method, the value of H/D KIE is 6.3 (300K). [Copyright &y& Elsevier]

Abstract: Equilibrium geometries, harmonic vibrational frequencies and the barrier heights of the internal rotation and inversion motion of methylamine (CH3NH2) conformers were calculated with the CCSD(T) method, in combination with the correlation consistent basis sets of Dunning. Valence and all electron correlation calculations were also carried out using the correlation consistent core and valence polarization triple-ζ basis set (cc-pCVTZ). Theoretical equilibrium geometries are in a general good agreement with available microwave and electron diffraction measurements. The best estimate results of the barrier heights for the internal rotation and inversion are, respectively, equal to 1.936 and 5.406kcal/mol. [Copyright &y& Elsevier]

Accurate equilibrium geometries, harmonic vibrational frequencies, and equilibrium rotational constants of the methyl radical were computed using coupled-cluster theory in combination with the cc-pVnZ and cc-pCVnZ basis sets of Dunning. Valence and all electron calculations were carried out. Using all electron correlations and CBS extrapolation, the re value is equal to 1.0758 Å, which is 0.0032 Å shorter than the experimental value of r0 (1.079 Å). The harmonic (ω1, ω2, ω3, and ω4) frequencies calculated using the CBS extrapolation differ from the experimental fundamental frequencies, respectively, by +142, +125, +21, and –82 cm-1. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [ABSTRACT FROM AUTHOR]

Accurate potential energy curves, dipole moment functions, dissociation energies and spectroscopic constants for three quartet electronic states (X4Σ−, A4Π and B4Σ−) of the CaN molecule are reported with the multireference singles and doubles configuration interaction methodology. Also, are present radiative transition probabilities and lifetimes for the A4Π–X4Σ−, B4Σ−–X4Σ− and B4Σ−–A4Π band systems. The ground state (X4Σ−) has an equilibrium distance equal to 4.410a0 and the dissociation energy is 0.85 eV. The A4Π has a shorter equilibrium distance equal to 4.142a0 and the B4Σ− has a much longer equilibrium distance, equal to 5.426a0. Radiative lifetimes for v′=0 are predicted to be 27 000, 0.256 and 565 μs for the A4Π–X4Σ−, B4Σ−–X4Σ− and B4Σ−–A4Π band systems, respectively. [Copyright &y& Elsevier]

The equilibrium geometries, harmonic vibration frequencies, and the rotational barrier of C2H6 have been calculated using CCSD(T) level of theory in combination with correlation-consistent basis sets of Dunning. The best estimate values of re(CH), re(CC) and θe(HCH) are 1.0895, 1.5240 A˚ and 107.66°, which are in close agreement with the experimental equilibrium geometry of 1.089±0.005 A˚ for re(CH), 1.524±0.003 A˚ for re(CC), and 106.9±0.5° for θe(HCH). The structure and harmonic vibrational frequencies for the CH4 molecule have also been analyzed. [Copyright &y& Elsevier]

Presents corrections to the article, entitled `Energetic and structural features of the CH[sub 4]+O([sup 3]P) CH[sub 3]+OH abstraction reaction: Does perturbation theory from a multiconfiguration reference state (finally) provide a balanced treatment of transition states?,' published in the volume 111 issue of the `Journal of Chemical Physics'.

Five electron-rich N N′−pyridylimine ligands, which form five-membered chelate ring when coordinate to a metal center, have been synthesized by the easily accessible condensation between 2-pyridinecarboxyaldhehyde and the corresponding substituted aniline in diethyl ether solution, in the presence of catalytic amount of p -toluenesulfonic acid. The reaction of N N′–pyridylimine ligands with [RuCl 2 (p -cym)] 2 (1) in the presence of excess of KPF 6 led to the formation of mononuclear adducts with general formula [RuCl(p -cym)(N N′)]PF 6 , where N N′ = N-phenyl-1-(pyridin-2-yl)methanimine (Amp) (2) , N-(4-chlorophenyl)-1-(pyridin-2-yl)methanimine (Clmp) (3) , N-(4-methylphenyl)-1-(pyridin-2-yl)methanimine (Memp) (4) , N-(4-tert-butylphenyl)-1-(pyridin-2-yl)methanimine (Tbump) (5) , N-(2,6-diethylphenyl)-1-(pyridin-2-yl)methanimine (Diemp) and N-[2,6-bis(propan-2-yl)phenyl]-1-(pyridin-2-yl)methanimine (Di i pmp) (7). Additionally, the reaction of 2-acetylbenzenolate (O O′) with (1) produces a less bulky neutral congener [RuCl(p -cym)(O O′)] (8). All complexes were isolated and fully characterized by molar conductivity, elemental analysis, cyclic voltammetry and spectroscopic methods, including single crystal X-ray diffraction of (4) , (7) and (8). The structures (2) – (7) were also optimized with the Density Functional Theory (DFT) and theoretical absorption spectra were obtained with TD-DFT formalism. The complexes (2) – (8) were applied as pre-catalyst in the transfer hydrogenation of the acetophenone and 4-methylacetophenone, showing good catalytic activity, with productivity up to 90%, and TOF up to 302 h−1 within 3 h of reaction; except for (8), which has no activity for the catalytic reduction performed in this work. A kinetic investigation using (3) and (7) as pre-catalysts showed that the time dependence for the production of 1-phenylethanol has a sigmoidal shape, with an induction time of 20 min. The catalytic activity of (3) is more sensitive to the temperature variation and its rate constant (k) increases faster than for (7). An Arrhenius plot reveals a smaller activation barrier (E a) for the rate-determining step for (7) than for (3) , E a = 14.75 and 49.38 k J mol−1, respectively. The Δ S ≠ values obtained from an Eyring plot suggest an associative mechanism in the transition state of the catalytic reactions. Image 1 • N N′−pyridylimine ligands form chelate ring with ruthenium-cymene moiety. • An accurate electronic spectroscopy argumentation was supported by TD-DFT. • The N N′ ligands do not partly or totally dissociate after variable potentials. • Electronic and steric hindrance of N N′−pyridylimine control the catalytic behavior. • ΔS≠/R values suggest an associative intermediate in the transition state. [ABSTRACT FROM AUTHOR]

The electronic states correlated to the first dissociation channel, around 25,500 cm −1 , of the AlC and GaC molecules have been investigated by CASSCF/MRCI methodology with aug-cc-pV5Z basis set. Our work focused on the accurate description of the potential energy curves, dissociation energies, transition moment functions, radiative lifetimes, dipole moments and molecular constants. The B 4 Σ − electronic state has been previously detected for AlC molecule and it is probably not detectable in GaC molecule due to the predissociative character which affects all its vibrational levels. The characterization of the GaC low-lying electronic states were carried out for the first time. [ABSTRACT FROM AUTHOR]

Graphene is regarded as one of the most promising materials for nanoelectronics applications. Defects play an important role in modulating its electronic properties and also enhance its chemical reactivity. In this work the reactivity of single vacancies (SV) and double vacancies (DV) in reaction with a hydrogen atom H r is studied. Because of the complicated open shell electronic structures of these defects due to dangling bonds, multireference configuration interaction (MRCI) methods are being used in combination with a previously developed defect model based on pyrene. Comparison of the stability of products derived from C H r bond formation with different carbon atoms of the different polyaromatic hydrocarbons is made. In the single vacancy case the most stable structure is the one where the incoming hydrogen is bound to the carbon atom carrying the dangling bond. However, stable C H r bonded structures are also observed in the five-membered ring of the single vacancy. In the double vacancy, most stable bonding of the reactant H r atom is found in the five-membered rings. In total, C H r bonds, corresponding to local energy minimum structures, are formed with all carbon atoms in the different defect systems and the pyrene itself. Reaction profiles for the four lowest electronic states show in the case of a single vacancy a complex picture of curve crossings and avoided crossings which will give rise to a complex nonadiabatic reaction dynamics involving several electronic states. [ABSTRACT FROM AUTHOR]

Accurate potential energy curves, dissociation energies, and molecular constants for several low-lying singlet and triplet electronic states of AsCl were investigated using the CASSCF/MRCI methodology, including the spin–orbit splitting with the aug-cc-pV5Z-DK basis set. Our results represent an improvement over previous the theoretical descriptions for the lowest lying states, as well as characterize another higher excited state not previously investigated. Transition probabilities and radiative lifetimes for the (1) 3 Π → X 3 Σ − band system were also predicted using Einstein spontaneous emission coefficients. [ABSTRACT FROM AUTHOR]

Highlights: [•] Low-lying electronic states of the GeB molecule. [•] Spin–orbit states. [•] Molecular constants. [•] Transition probabilities. [ABSTRACT FROM AUTHOR]

Highlights: [•] Accurate structures of aluminum clusters: Al n x (n =1–9, x =0, ±1). [•] Electron affinities and ionization potential. [•] DFT and CCSD(T) electronic calculations. [ABSTRACT FROM AUTHOR]

Abstract: Thermochemical and kinetics properties of the hydrogen abstraction and addition processes of the reaction were computed using high-level ab initio and DFT approximation methods with aug-cc-pVXZ (X=T,Q) basis set. The CCSD (T)/CBS//BB1K/aug-cc-pVTZ results for classical barrier height are 13.1 and 15.0kcal/mol for the abstraction and addition reactions, respectively. The thermal rate constants were calculated using the dual-level direct dynamics by variational transition state theory with the BB1K potential energy surface and thermochemical properties corrected with the CCSD (T)/CBS//BB1K/aug-cc-pVTZ results. The rate constants calculated show that the variational and tunneling effects play a relevant role only for the abstraction reaction. [Copyright &y& Elsevier]

Abstract: The lowest singlet and triplet states of AlP3, GaP3 and BP3 molecules with Cs, C2v and C3v symmetries were characterized using the B3LYP functional and the aug-cc-pVTZ and aug-cc-pVQZ correlated consistent basis sets. Geometrical parameters and vibrational frequencies were calculated and compared to existent experimental and theoretical data. Relative energies were obtained with single point CCSD(T) calculations using the aug-cc-pVTZ, aug-cc-pVQZ and aug-cc-pV5Z basis sets, and then extrapolating to the complete basis set (CBS) limit. [Copyright &y& Elsevier]

Abstract: Accurate potential energy curves, dissociation energies and molecular constants for several low-lying singlet and triplet electronic states of MgS were investigated using the CASSCF/MRCI methodology, and the cc-pVQZ basis set. Our results represent an improvement over previous theoretical description for the lowest lying states, characterize some higher excited states not previously investigated, and also confirm the assignment of the B1Σ+ excited state investigated experimentally. Transition probabilities and radiative lifetimes were also predicted using Einstein spontaneous emission coefficients. [Copyright &y& Elsevier]

Abstract: Accurate potential energy curves, dissociation energies and spectroscopic constants for several low-lying doublet and quartet electronic states of CaAl were investigated using the CASSCF/MRCI methodology, and the cc-pVQZ basis set. Our results represent an improvement over a previous theoretical description, and also characterizes new higher excited states not previously investigated, thus confirming the assignment of four excited states investigated experimentally. With the theoretical transition moment functions, transition probabilities and radiative lifetimes were estimated via Einstein spontaneous emission coefficients. [Copyright &y& Elsevier]

Abstract: Equilibrium geometries, harmonic vibrational frequencies of the C2h and D2h conformers of the hydrazine ion (N2H4 +) were calculated with the CCSD(T) method, in combination with the correlation consistent basis sets of Dunning. Valence and all electron correlation calculations were also carried out using the correlation consistent core and valence polarization triple-zeta basis set (cc-pCVTZ). The adiabatic ionization potential of hydrazine were also calculated using CCSD(T) and CASSCF/MRCI with the CBS extrapolation with the best results respectively equal to 8.07 and 7.81eV, which are closer to experimental data, equal to 8.1±0.15 eV. [Copyright &y& Elsevier]

Abstract: The low-lying electronic states of GeC are investigated at a high level of correlation treatment using the CASSCF/MRSDCI approach, and the aug-cc-pVQZ basis set. Potential energy curves, spectroscopic properties, dipole moment and transition moment functions are given for all electronic singlet, triplet and quintet states that dissociate into the first channel. Transition probabilities and radiative lifetimes are also predicted using the Einstein coefficients. [Copyright &y& Elsevier]

Abstract: In this work is presented, for the first time, an accurate spectroscopic characterization of the lowest-lying doublet and quartet states of BeAl molecule. We used a high level CASSCF/MRCI correlation methodology and the aug-cc-pVQZ basis set. The behavior of the dipole moment and the transition dipole moment functions are described, and transition probabilities and radiative lifetimes are also predicted using the Einstein coefficients. [Copyright &y& Elsevier]

Abstract: The low-lying electronic states of MgAl are investigated at a high level of electron correlation treatment using the CASSCF/MRCI approach, and the aug-cc-pVQZ basis set. Besides the confirmation of the ground state (X 2Π) and the first excited state ((1) 2Σ+), this study also provides a very accurate spectroscopic characterization of the lowest-lying doublet and quartet states. The behavior of the dipole moment and the transition dipole moment functions with internuclear distance are also described. Relative intensities for the (2) 2Π→X 2Π, (3) 2Π→X 2Π and (1) 2Δ→X 2Π band systems are predicted by the Einstein coefficients. [Copyright &y& Elsevier]

Abstract: High-level multireference calculations are reported for the low-lying electronic states of GaN. Using the CASSCF/MRSDCI approach and the aug-cc-pVQZ basis set a detailed analysis is given for the 22 electronic states that dissociate in the first two channels. The ground state is confirmed as (X3Σ−) but the first excited state ((1)3Π) is found to be very close in energy. A very accurate spectroscopic characterization is made for the lowest-lying triplet and singlet states. The behavior of dipole moment and transition dipole moment with internuclear distance is also described. Relative intensities are predicted using the Einstein coefficients. [Copyright &y& Elsevier]

The low-lying electronic states of PCl are investigated at a high level of correlation treatment using the CASSCF/MRSDCI approach, and the aug-cc-pVQZ-g basis set augmented with diffuse functions. The potential energy curves characterize unambiguously the complex structure of the electronic states, identifying avoided crossing regions among the 3Π states of relevance to experimentalists. Besides improving the accuracy of spectroscopic data upon previous theoretical studies, it unequivocally determines the dissociation energy of the ground state. The behavior of the dipole moment, transition dipole moment, and spin–orbit coupling constants with internuclear distance is also described. Relative intensities are predicted by the Einstein coefficients. [Copyright &y& Elsevier]

Accurate potential energy curves, transition moments, spectroscopic constants, radiative transition probabilities, and lifetimes for the states X 3Σ-, (1) 3Π, and (2) 3Σ- of BeC, MgC, and CaC are reported using high level calculations. Diagonal transitions dominate for the (2) 3Σ- → X 3Σ- system, with band origins falling at 745, 648, and 770 nm, and an intensity ratio of 6,3,1, respectively for BeC, MgC, and CaC. Radiative lifetimes for v′=0 are equal to 0.48, 1.45, and 3.29 μs for the state (2) 3Σ-, and equal to 13.57, 10.44, and 9.62 μs for the state (1) 3Π for BeC, MgC, and CaC. [Copyright &y& Elsevier]

The tautomeric equilibrium of benzotriazole was investigated using Hartree–Fock (HF), MP2, B3LYP and coupled cluster methodologies with a series of basis set. The HF and MP2 results present a clear preference for the 1H and 2H tautomers, respectively, while with B3LYP and coupled cluster both structures have a very similar energy. The inclusion of zero point energy was proved to be necessary when using B3LYP and coupled cluster methods, leading to a preference for the 1H tautomer. The geometric parameters obtained with MP2 and B3LYP using aug-cc-pVTZ basis set are very similar to experimental data of 1H. The frequencies also provided a great concordance with experimental data with the correct use of scale factor. Dipole moment and rotational constants were also analysed. [Copyright &y& Elsevier]

Accurate potential energy curves, dipole moment functions, dissociation energies and spectroscopic constants for six electronic states (3Σ−,3Π,5Σ−,1Δ,1Π,1Σ+) of the CaC molecule are reported with the multireference singles and doubles configuration interaction methodology. The ground state has symmetry 3Σ−, with a dissociation energy (D0) equal to 1.94 eV. The 5Σ− state is the first excited state lying 695 cm−1 above the 3Σ− ground state. The 1Δ and 3Π states are the second and third excited states separated, respectively, by 10 763 and 12 167 cm−1 from the 3Σ− ground state. [Copyright &y& Elsevier]

Ultracold environments composed by atoms or molecules offer an opportunity to study chemical reactions at the quantum-state level, for simulation of solid-state systems, as qubits in quantum computing, and for test fundamental symmetries. Those ultracold conditions formed by molecules can be obtained from cryogenic buffer gas, via supersonic expansion, followed by deceleration or from the laser cooling process. Diatomic alkaline earth monofluoride molecules have been shown as great candidates for the laser cooling process. In this sense, the present work focuses on the characterization of the low-lying doublet electronic states correlated to the first dissociation channel of the alkaline earth monofluorides diatomic molecules MF (M = Be, Mg and Ca). The developed state-of-the-art methodology was based on a qualitative analysis of the diatomic electronic structure, employing a hypothetical potential energy curve or by a simple molecular orbital diagram combined with bond order analysis. The potential energy curves, excitation and dissociation energies, and various sets of spectroscopic parameters were calculated by the MRCI/cc-pV5Z methodology. Transition probabilities for emission and radiative lifetimes among the characterized electronic states were also calculated for the (A)2Π ⟶ (X)2Σ+ electronic transition. Comparing the spectroscopy properties, we were able to indicate the CaF molecule as the best candidate molecule for laser cooling devices among the studied molecules. Unlabelled Image • Low-lying electronic states of the BeF, MgF and CaF molecules • The ionic and covalent character description of polar molecules • CaF molecule is a good candidate for laser cooling • Emission spectra of the (A)2Π ⟶ (X)2Σ+ electronic transition [ABSTRACT FROM AUTHOR]