Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Radiative and predissociative lifetimes of the A 2Σ+ state (v′=0,1) of SH and SD: A highly correlated theoretical investigation (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 2178-2187 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Doublet and quartet states of the HS radical correlating with H(2S)+S(3P,1D,1S) were investigated by ab initio calculations, at the CASSCF-MRCI/aug-cc-pV5Z level of theory. Molecular parameters and spectroscopic constants obtained for both the ground (X 2Π) and the first excited (A 2Σ+) states represent the best overall theoretical description of this system to date. Transition moments, transition probabilities, and radiative and predissociative lifetimes were also determined for the X 2Π–A 2Σ+ system. The values calculated for the radiative lifetimes of the A state show that previous results were too large. Theoretical predissociative lifetimes, although quite sensitive to the region of crossing of the potential energy curves, reproduce the experimental trends. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1381577
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    A converged calculation of the energy barrier to internal rotation in the ethylene–sulfur dioxide dimer (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 2476-2482 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Geometrical parameters for the equilibrium (MIN) and lowest saddle-point (TS) geometries of the C2H4(centered ellipsis)SO2 dimer, and the corresponding binding energies, were calculated using the Hartree–Fock and correlated levels of ab initio theory, in basis sets ranging from the D95(d,p) double-zeta basis set to the aug-cc-pVQZ correlation consistent basis set. An assessment of the effect of the basis set superposition error (BSSE) on these results was made. The dissociation energy from the lowest vibrational state was estimated to be 705±100 cm−1 at the basis set limit, which is well within the range expected from experiment. The barrier to internal rotation was found to be 53±5 cm−1, slightly higher than the (revised) experimental result of 43 cm−1, probably due to zero-point vibrational effects. Our results clearly show that, in direct contrast with recent ideas, the BSSE correction affects differentially the MIN and TS binding energies and so has to be included in the calculation of small energy barriers such as that in the C2H4(centered ellipsis)SO2 dimer. Previous reports of positive MP2 frozen-core binding energies for this complex in basis D95(d,p) are confirmed. The anomalies are shown to be an artifact arising from an incorrect removal of virtual orbitals by the default frozen-core option in the GAUSSIAN program. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1385367
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Ab initio investigation of internal rotation in the ethylene–sulfur dioxide dimer (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 4184-4188 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The phenomenon of tunneling motion in the C2H4...SO2 dimer has been studied in the ab initio Hartree–Fock (HF) and Møller–Plesset second-order perturbation theory (MP2) levels, employing the DZP basis set. Basis set superposition errors (BSSE) were accounted for using the counterpoise correction method. A simple model for treating the problem in one dimension was utilized, where coupling of intramolecular vibration and dimer internal rotation have been neglected. A comparative study between two potentials was carried out. The first potential is based on pointwise ab initio calculations of the intermolecular potential energy surface (PES) including BSSE correction, and the second is based on the expression VN=V0 [1−cos(Nα)]/2, where V0 was obtained from the ab initio fully optimized equilibrium and transition state structures. The resultant Hamiltonian was solved using the variational method, and the calculated splitting of transition frequencies compared with experimental data. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469465
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Ab initio MP2 study of the HF ... ClF complex using various extended basis sets and bond functions (1996)
    Springer
    Theoretical chemistry accounts 93 (1996), S. 333-342 
    Details
    ISSN: 1432-2234
    Keywords: van der Waals complex ; Transition states ; Extended basis sets ; Bond functions ; Electronic correlation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The stationary points on the intermolecular potential energy surface (PES) for the HF ... ClF complex have been investigated at the second-order Møller-Plesset perturbation theory (MP2) level using various extended bais sets, including diffuse functions, and also bond functions. The last ones were placed at different intermolecular positions, for distinct stationary points. The basis set superposition errors (BSSE) were accounted for using the counterpoise method. Besides the anti-H-bonded and H-bonded minimum energy structures, four transition state structures were also located on the PES. It was shown that higher polarization functions are required for the description of the anti H-bonded isomer and diffuse functions had to be included for the H-bonded isomer. The bond functions are able to replace thef (Cl, F) andd(H) polarization functions at a lower computational cost. However, for the H-bonded isomer intramolecular electron correlation also plays an important role. So we have to use diffuse nucleus centered polarization functions for an adequate description of intermolecular and intramolecular correlation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01129214
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Ab initio MP2 study of the HF …ClF complex using various extended basis sets and bond functions (1996)
    Springer
    Theoretica chimica acta 93 (1996), S. 333-342 
    Details
    ISSN: 0040-5744
    Keywords: Key words: van der Waals complex ; Transition states ; Extended basis sets ; Bond functions ; Electronic correlation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  The stationary points on the intermolecular potential energy surface (PES) for the HF…ClF complex have been investigated at the second-order Møller–Plesset perturbation theory (MP2) level using various extended bais sets, including diffuse functions, and also bond functions. The last ones were placed at different intermolecular positions, for distinct stationary points. The basis set superposition errors (BSSE) were accounted for using the counterpoise method. Besides the anti-H-bonded and H-bonded minimum energy structures, four transition state structures were also located on the PES. It was shown that higher polarization functions are required for the description of the anti H-bonded isomer and diffuse functions had to be included for the H-bonded isomer. The bond functions are able to replace the f (Cl, F) and d(H) polarization functions at a lower computational cost. However, for the H-bonded isomer intramolecular electron correlation also plays an important role. So we have to use diffuse nucleus centered polarization functions for an adequate description of intermolecular and intramolecular correlation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01129214
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Ab initio conformational analysis of cyclooctane molecule (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 19 (1998), S. 524-534 
    Details
    ISSN: 0192-8651
    Keywords: ab initio conformational analysis ; cyclooctane molecule ; potential energy surface ; Hartree-Fock theory ; Møller-Plesset theory ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The potential energy surface (PES) for the cyclooctane molecule was comprehensively investigated at the Hartree-Fock (HF) level of theory employing the 3-21G, 6-31G, and 6-31G* basis sets. Six distinct true minimum energy structures (named B, BB, BC, CROWN, TBC, and TCC1), characterized through harmonic frequency analysis, were located on the multidimensional PES. Two transition state structures were also located on the PES for the cyclooctane molecule. Electron correlation effects were accounted for using the Møller-Plesset second-order perturbation theory (MP2) approach. The predicted global minimum energy structure on the ab initio PES for the cyclooctane molecule is the BC conformer. A gas phase electron diffraction study at 300 K suggested a conformational mixture while an NMR study in solution at 161.5 K predicted the BC conformer as the predominant form. The equilibrium constants reported in the present study, which were evaluated from the ab initio calculated total Gibbs free energy change values, were in good agreement with both experimental investigations. The ab initio results showed that the low temperature condition significantly favored the BC conformer while above room temperature both BC and CROWN structures can coexist.   © 1998 John Wiley & Sons, Inc.   J Comput Chem 19: 524-534, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...