On the ab initio determination of higher-order force constants at nonstationary reference geometries

Allen, Wesley D.; Császár, Attila G.
February 1993
Journal of Chemical Physics;2/15/1993, Vol. 98 Issue 4, p2983
Academic Journal
Several complementary analyses have been performed in an investigation of the use of reference geometric structures which are not stationary at a given level of theory in the prediction of improved equilibrium anharmonic molecular force fields. Diatomic paradigms for the procedure were established by constructing empirical potential energy functions for the nitrogen and fluorine molecules which not only reproduce the available Rydberg–Klein–Rees data but also provide reliable derivatives through fourth order for ranges of 0.4 Å or greater around the equilibrium bond distance. For comparison, analogous curves were determined at the double-ζ plus polarization (DZP) restricted Hartree–Fock (RHF) level of theory, and the quartic force fields for N2 and F2 were also obtained at the experimental re structures using a (8s5p3d2f1g) basis set and the coupled-cluster singles and doubles method augmented by a perturbative contribution from connected triple excitations [CCSD(T)]. The results substantiate the ability of RHF theory to predict correlation-quality, higher-order force constants if an accurate reference geometry from experiment or a higher level of theory is employed. The theoretical foundations of this technique as applied to polyatomic molecular systems have been systematically explored. Mechanisms were analyzed which address the nonzero force dilemma by using various choices of internal coordinates to shift the equilibrium point of theoretical potential energy surfaces. Examples are presented in which the variations in predicted spectroscopic constants arising from different shift coordinate sets are non-negligible. A Cartesian projection scheme for higher-order force fields was developed and implemented to avert internal-coordinate dependences; formulas for higher-order projection matrices and higher-order derivatives of the external variables of a molecular system were concurrently derived. A formalism for the transformation...


Related Articles

  • The van der Waals potential-energy surfaces and the structures of ArClF and ArCl2. Tao, Fu-Ming; Klemperer, William // Journal of Chemical Physics;7/1/1992, Vol. 97 Issue 1, p440 

    The potential-energy surfaces of the ArClF and ArCl2 complexes are determined by the Hartree-Fock (HF) and Mo\ller–Plesset calculations (up to MP4) in an efficient basis set of 6-31+G(2df ) for the intermolecular energy. The interaction energies are calculated by the supermolecular...

  • Polarization consistent basis sets: Principles. Jensen, Frank // Journal of Chemical Physics;11/22/2001, Vol. 115 Issue 20, p9113 

    The basis set convergence of Hartree–Fock energies for the H[sub 2], H[sub 3][sup +], C[sub 2], N[sub 2], N[sub 4], O[sub 2], O[sub 3], F[sub 2], HF, and CH[sub 4] molecules is analyzed using optimized basis functions. Based on these analysis a sequence of polarization consistent basis...

  • Analytical time-dependent Hartree–Fock schemes for the evaluation of the hyper-Raman intensities. Quinet, Olivier; Champagne, Benoı⁁t // Journal of Chemical Physics;8/8/2002, Vol. 117 Issue 6, p2481 

    Two analytical procedures based on the time-dependent Hartree-Fock (TDHF) scheme are elaborated to evaluate the first derivatives of the dynamic first hyperpolarizability with respect to atomic Cartesian coordinates. In the first scheme, the mixed third-order TDHF equations are solved...

  • Zero potential energy criterion applied to Hartree–Fock wave functions. Koga, Toshikatsu // Journal of Chemical Physics;10/1/1988, Vol. 89 Issue 7, p4209 

    The zero potential energy criterion, which is a necessary condition for the exact wave function, is applied to Hartree–Fock wave functions for a closed-shell system with doubly occupied spatial orbitals. With the help of the known long-range asymptotic behavior of Hartree–Fock...

  • On the choice of orbital bases for configuration interaction. Tarantelli, F.; Cederbaum, L. S. // Journal of Chemical Physics;10/1/1988, Vol. 89 Issue 7, p4170 

    We study the CI energy dependence on one-particle orbital bases obtained as SCF solutions of a general parametrized Fock operator which reduces to the Hartree–Fock mean field as a special case. In the case of single excitation CI, exact analytical expressions are derived for the curvature...

  • Ab initio studies of the reactions of Cu([sup 2]S, [sup 2]D, and [sup 2]P) with SiH[sub 4] and GeH[sub 4]. Luna-Garcı´a, H.; Ramı´rez-Solı´s, A.; Castillo, S. // Journal of Chemical Physics;1/15/2002, Vol. 116 Issue 3, p928 

    The interactions of Cu(²S:3d[sup 10]4s¹ ²D:3d[sup 9]4s², and2p:3d[sup 10]4p¹) with SiH[sub 4] and GeH[sub 4] were studied by means of Hartree-Fock-SCF and multiconfigurational-SCF followed by variational and multireference second order Möller-Plesset perturbational...

  • Anisotropic repulsive potential energy surfaces from Hartree–Fock calculations for HeCO2 and HeOCS. Keil, Mark; Rawluk, Leslie J.; Dingle, Thomas W. // Journal of Chemical Physics;5/1/1992, Vol. 96 Issue 9, p6621 

    Hartree–Fock calculations are presented for the repulsive interactions of He with CO2 and OCS. The results are well described by parametrizing the anisotropic potential energy surface as a sum over interactions between He and each atom of the molecule. The interaction of He with the...

  • Comment on: Time-dependent Hartree approximation applied to the photodissociation of ICN. Guo, Hua; Schatz, George C. // Journal of Chemical Physics;11/15/1992, Vol. 97 Issue 10, p7853 

    Comments on a study on time-dependent Hartree approximation applied to the photodissociation of ICN, a prototypical model for studying direct photodissociation in the gas phase. Empirical potentials proposed to account for the bimodal rotational state distribution of the CN fragment;...

  • Computed self-consistent field and singles and doubles configuration interaction spectroscopic data and dissociation energies for the diatomics B2, C2, N2, O2, F2, CN, CP, CS, PN, SiC, SiN, SiO, SiP, and their ions. McLean, A. D.; Liu, B.; Chandler, G. S. // Journal of Chemical Physics;12/1/1992, Vol. 97 Issue 11, p8459 

    Single configuration self-consistent field (SCF) calculations near the Hartree–Fock limit, and singles and doubles configuration-interaction (CI)(SDCI) calculations from this single SCF configuration have been performed for the ground and selected excited states of the molecules B2+, B2,...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics