Anharmonic force fields from analytic CCSD(T) second derivatives: HOF and F2O

Abstract

Articles you may be interested inComparison of some dispersion-corrected and traditional functionals with CCSD(T) and MP2 ab initio methods: Dispersion, induction, and basis set superposition error J. Chem. Phys. 137, 134109 (2012); 10.1063/1.4755990Anharmonic force field and vibrational dynamics of CH2F2 up to 5000 cm−1 studied by Fourier transform infrared spectroscopy and state-of-the-art ab initio calculations Infrared absorption spectra of matrix-isolated cis, cis-HOONO and its ab initio CCSD(T) anharmonic vibrational bandsThe recent implementation of analytic second derivatives for CCSD͑T͒ ͑coupled cluster theory with single and double excitations augmented by a perturbational treatment of connected triple excitations͒ has been combined with a numerical finite difference procedure to calculate cubic and semidiagonal quartic force fields. Computational details of this approach are outlined. Applications are reported for HOF and F 2 O. The CCSD͑T͒ results are in excellent agreement with experiment and represent a substantial improvement over the results obtained from MP2 ͑Mo "ller-Plesset second-order perturbation theory͒.

Effects of Electron Correlation and Scalar Relativistic Corrections on the Thermochemical and Spectroscopic Properties of HOF

“…23 The ab initio force constants incorporated into this force field were obtained at the CCSD/TZP//CCSD/TZP (quadratic and cubic) and SCF/TZP//CCSD/TZP (quartic) levels of theory. 23 There is no doubt that the CCSD(T) results of Breidung et al 24 and the present results are more reliable because the perturbative inclusion of triple excitations in the CCSD(T) method represents a significant improvement over CCSD. Use of some of these force constants in the place of those of Thiel et al 23 along with available experimental data may lead to a more accurate empirical force field for HOF and, perhaps, even better agreement between the calculated force constants presented in this work and those that are determined by constrained minimization.…”

“…In these cases, the absolute differences between the CBS + CV + SR constants and experimental values are 28% and 80%, respectively. The CCSD(T)/cc-pVTZ values for these constants obtained by Breidung et al 24 also have large absolute differences (18.3% and 42.6%, respectively) from the experimental values. Given the ability of high-level computational chemistry to accurately predict a wide range of molecular properties, and given the many difficulties of accurately analyzing experimental molecular spectra, it may not be entirely unreasonable to suspect that the experimental constants may be in error in at least these two cases.…”

“…Since the CCSD(T)/AVDZ results are of limited interest, we have omitted them in favor of the CCSD-(T) results of Breidung et al, 24 in which the quadratic force constants were obtained at the CCSD(T)/cc-pVQZ level and the cubic and quartic force constants at the CCSD(T)/cc-pVTZ level of theory using analytical second derivatives. The present results are comparable to those of Breidung et al in most cases, but a few significant differences do exist, e.g., the force constants (2,0,1), (0,0,4), (3,1,0), (1,3,0), (3,0,1), (0,3,1), and (1,2,1).…”

“…The latter 4 described a global potential energy surface derived partially from a quadratic force field calculated from experimental vibrational frequencies and partially from SCF calculations. The first calculation of spectroscopic properties and an anharmonic force field for HOF that included electron correlation effects appears to be the coupled cluster singles and doubles (CCSD) investigations of Thiel et al 23 Halonen and Ha 20 constructed an empirical quartic force field by a constrained least-squares fit to available experimental vibration-rotation data supplemented by several ab initio force constants from Thiel et al The most accurate theoretical calculations of the spectroscopic constants and anharmonic force field of HOF to date appears to be that of Breidung et al, 24 who used the CCSD method with perturbative triples, CCSD(T), 25,26 making use of the then-recently implemented analytic second derivatives 27 to obtain a quartic force field. To the best of our knowledge, refs 23 and 24 represent the only reliable theoretical estimates of the spectroscopic constants of the HOF molecule available at this time.…”

The X̃ 2B1, B22, A12, and A22 states of oxygen difluoride cation (F2O+): High-level ab initio calculations and simulation of the ultraviolet photoelectron spectrum of F2O

“…For the X 1 A 1 state of neutral F 2 O, the anharmonic force field at the CCSD͑T͒ level ͑quadratic force field from CCSD͑T͒/cc-pVQZ, cubic, and quartic force field from CCSD͑T͒/cc-pVTZ calculations͒ has been reported by Breidung and co-worker. 19 Variational calculation of vibrational wave functions was also performed employing the best PEF from Ref. 19.…”