3,311 research outputs found
Al³+ ? He: stability and spectroscopy
No full textThe complex between the trication, Al3+, and a helium atom is investigated using high-level ab initio calculations. In addition, the avoided crossing between the ground state Al3+-He potential energy curve, and the lowest repulsive charge transfer state, Al3+...He+, is investigated using CASSCF + MRCI calculations: it is found that the avoided crossing is very sharp. Vibrational and rotational spectroscopic parameters are calculated. It is concluded that the Al3+-He complex is kinetically stable and should be observable
Preliminary ab initio study of the quartet states of the complex formed between NO(X 2?) and O2(X 3?g?)
No full textWe present the results of a preliminary study of the quartet states of the complex formed between the ground-state NO(X 2?) and the ground-state O2(X 3?g?) molecules. Geometry optimizations are performed at the UQCISD/6-31+G* and UQCISD/6-311+G(2d) level. Binding energies are then calculated for the three lowest energy isomers at the RCCSD(T)/aug-cc-pVQZ level. The lowest energy isomer is found to be a T-shaped C2v NO(O2) structure, with a De value of 110 cm?1, after correction for BSSE. The favoured geometry seems to suggest that electron repulsion is an important consideration in this species
The structure and stability of the complex formed between NO+ and CO
No full textThe cationic complex formed between NO+ and CO is investigated using high-level ab initio calculations. Geometries were optimized rat at the MP2/6-31+G* and then the MP2/aug-cc-pVTZ level of theory. At the latter level all linear isomers were found to be transition states. Two minima were found, corresponding to skewed structures. Finally the relative energies were calculated at the CCSD(T)/aug-cc- pVQZ//MP2/aug-cc-pVTZ level of theory, correcting for basis set superposition error. The binding energy of the lowest energy isomer was calculated to be 2730 cm-1. Finally, density functional theory (DFT) methods were concluded to overestimate the interaction
Preliminary calculations on the Na-N-2 complex
No full textHigh-level, RCCSD(T), calculations are performed on the molecular complex formed between a Na(S-2) atom and a N-2(X(1)Sigma(g)(+)) 9 molecule, using large basis sets. The complex is found to have a linear global minimum, with a D, value of only 24 cm(-1). The zeropoint energy is estimated to be around 16 cm(-1), suggesting that this is a very floppy complex. In addition, a T-shaped saddle-point lies only 7.5 cm(-1) above the potential energy minimum
Heats of formation of NaOH and NaOH+: ionization energy of NaOH
No full textRCCSD(T) calculations combined with large basis sets are employed to obtain the heats of formation and dissociation energies of NaOH and NaOH+. Our best values are ?H(f)(NaOH,0 K) = -44 +/- 1 kcal mol(-1) and D-0 = 79 +/- 1 kcal mol(-1). The ground state of NaOH+ is a X(2)Pi state, which is split by a very small Renner-Teller interaction. We calculate AIE (NaOH) = 7.87 +/- 0.05 eV, ?H(f)(NaOH+,0 K) = 137 +/- 1 kcal mol(-1), and D-0 = 16 +/- 1 kcal mol(-1). The proton affinity of NaO(X(2)?) is derived as 250 +/- 1 kcal mol(-1). In addition, we conclude that, experimentally, the Vibrational frequencies of neither NaOH nor NaOH+ are known with any reliability
The ionization energy of KO2 ((X)over-tilde(2)A(2)) and dissociation energies of KO2 and KO2+
No full textRCCSD(T) calculations, with an effective core potential for the inner electrons of potassium, and large polarized valence basis sets, have been used to calculate ionization energies of KO2. In addition, the binding energies of the ground electronic states of KO2, (X)over-tilde(2)A(2), and KO2+, X(3)Sigma(-), have been determined. Comparison with previous values is made, where possible, and an estimate made of the errors in our calculations. The binding energy of KO2+ is found to be very limited. It is concluded that the rôle of KO2+ in the upper atmosphere will be small
Heats of formation of LiOH(X1?+) and LiOH+(X2?): the ionization energy of LiOH
No full textRCCSD(T) calculations combined with large basis sets are employed to obtain the heats of formation of LiOH and LiOH+; in addition, the first adiabatic and vertical ionization energies of LiOH are obtained. Our best values are: ?H(f)(LiOH, 0 K) = -57.0+/--0.5 kcalmol(-1) and D-0 = 104+/-1 kcalmol(-1). The ground state of LiOH+ is a quasi-linear Renner-Tefler X2? state and AIE(LiOH) = 8.91+/-0.03 eV. ?H(f)(LiOH+, 0 K) = 148+/-2 kcalmol(-1) and D-0 = 23+/-1 kcalmol(-1). The proton affinity of LiO(X2?) is derived as 230+/-1 kcalmol(-1)
Spectroscopy and thermodynamics of LiS/NaS (X²? and A²?+) and LiS+/NaS+(X³?¯and A³?)
No full textPotential energy curves are calculated for the X(2)Pi and A(2)Sigma(+), states of LiS and NaS and the X(3)Sigma(-) and A(3)Pi states of LiS+ and NaS+. The RCCSD(T)/aug-cc-pVXZ levels of theory are employed (X = Q, 5 and infinity), where the infinityZ results are obtained at each bond distance, R, employing a two-point extrapolation to the basis set limit. From the three sets of curves, spectroscopic constants, ionization and dissociation energies are derived. Comparison is made to available experimental and calculational results
Winter Habitat Characteristics of Black Faced Spoonbill (Platalea minor) at Chi-Ku, Taiwan
No full textIonization energy of KOH and the dissociation energies of KOH and KOH+
No full textHigh level ab initio, up to RCCSD(T), and B3LYP calculations were employed to calculate thermochemical properties for KOH and KOH+. Basis sets were of both all-electron and effective core potential (ECP) types: in both cases large, flexible valence basis sets were used, and the largest basis sets were of quintuple-zeta quality. Both KOH and KOH+ were found to be linear; in the latter case, the Renner-Teller effect is discussed. The results are close to convergence with regard to both basis sets and levels of theory. The most reliable quantities are: first AIE(KOH)=7.38+/-0.02 eV; D-0(K...OH)=82+/-1 kcal mol(-1); D-0(K+...OH)=11.4+/-1 kcal mol(-1); DeltaH(f)(KOH, 298 K) = -53+/-1 kcal mol(-1); and DeltaH(f)(KOH+, 298 K)=119+/-1 kcal mol(-1)
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