1,721,138 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
The heaviest group 2 dihalide: RaAt2
No full textHigh level ab initio calculations, up to (R)CCSD(T) as well as B3LYP have been performed on, radium diastatide, RaAt2, employing effective core potentials augmented with large, flexible valence basis sets. RaAt2 is found to have a bent equilibrium geometry, with a bond angle of similar to134.50, but a very low barrier to linearity. In addition, we performed calculations on the lowest cationic states, and calculate the first adiabatic ionization energy to be 7.41 eV, corresponding to a X(2)B(2) - X(1)A(1) process. We also calculate the energies of the lowest neutral states and find that RaAt2 is likely to absorb in the ultraviolet
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
Ionization 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)
Structure and thermodynamics of KO3 and KO3+
No full textThe KO3 and KO3+ species are both calculated to have C-2v diamond structures, with a trans planar geometry lying higher in energy. For the cation, the energy difference between these two structures is only similar to1 ~ mol(-1). We calculate binding energies of the two species and obtain values of 126 +/- 1 and 8 +/- 1 kcal mol(-1), for K+...03 and K+...O3, respectively. The adiabatic ionization energy is determined as 7.0 +/- 1 eV and DeltaH(f)(0 K) values of -17 +/- 2 and 149 +/- 2 kcal mol(-1) are obtained for KO3 and KO3+ respectively.
Ground electronic states of RbO2+, CsO2+ and FrO2: The ionization energies of RbO2 and CsO2
No full textCalculations are performed to establish the ground electronic states of RbO2+, CsO2+, and FrO2. In the case of the cations, both linear and C-2 nu orientations were considered; for FrO2, the two lowest electronic states, (2)A(2) and B-2(2), were considered in C-2 nu symmetry. In addition, calculations were also performed on the (X) over tilde (2)A(2) ground states of RbO2 and CsO2 to derive ionization energies. Binding energies and heats of formation are also derived. The bonding in FrO2 is found to be less ionic than that of RbO2 and CsO2
Spectroscopy and thermodynamics of KO+
No full textHigh-level RCCSD(T) calculations are employed to generate potential energy curves for the (3)Sigma(-) and (3)Pi states of KO+. First, these curves are employed to obtain spectroscopic constants for the two cationic states. Second, the curves are employed together with our previous results on KO, to obtain accurate ionization energies for the KO+ - KO processes, for the states involved. We conclude that the first adiabatic ionization energy of KO is 6.98 +/- 0.05 eV, with D-0(KO+) = 1460 +/- 20 cm(-1)
Simulation of the single-vibronic-level emission spectra of HAsO and DAsO
No full textThe single-vibronic-level (SVL) emission spectra of HAsO and DAsO have been simulated by electronic structure/Franck-Condon factor calculations to confirm the spectral molecular carrier and to investigate the electronic states involved. Various multi-reference (MR) methods, namely, NEVPT2 (n-electron valence state second order perturbation theory), RSPT2-F12 (explicitly correlated Rayleigh-Schrodinger second order perturbation theory), and MRCI-F12 (explicitly correlated multi-reference configuration interaction) were employed to compute the geometries and relative electronic energies for the X˜1A? and A˜1A?? states of HAsO. These are the highest level calculations on these states yet reported. The MRCI-F12 method gives computed T0 (adiabatic transition energy including zero-point energy correction) values, which agree well with the available experimental T0 value much better than previously computed values and values computed with other MR methods in this work. In addition, the potential energy surfaces of the X˜1A? and A˜1A?? states of HAsO were computed using the MRCI-F12 method. Franck-Condon factors between the two states, which include anharmonicity and Duschinsky rotation, were then computed and used to simulate the recently reported SVL emission spectra of HAsO and DAsO [R. Grimminger and D. J. Clouthier, J. Chem. Phys. 135, 184308 (2011)]. Our simulated SVL emission spectra confirm the assignments of the molecular carrier, the electronic states involved, and the vibrational structures observed in the SVL emission spectra but suggest a loss of intensity in the reported experimental spectra at the low emission energy region almost certainly due to a loss of responsivity near the cutoff region (?800 nm) of the detector used. Computed and experimentally derived re (equilibrium) and/or r0 {the (0,0,0) vibrational level} geometries of the two states of HAsO are discussed
- …
