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
Filter
  • 2000-2004
  • 1985-1989  (22)
  • 1987  (22)
Source
Material
Years
  • 2000-2004
  • 1985-1989  (22)
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Theoretical study of the N+2 Meinel system (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 4716-4721 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The potential curves for the X 2Σ+g and A 2Πu states of N+2 are determined using generally contracted atomic natural orbital Gaussian basis sets and large CASSCF/multireference CI wave functions. The dependence of the X 2Σ+g– A 2Πu electronic transition moment on internuclear distance is accurately determined, and is shown to differ significantly from previous determinations. However, the theoretically determined lifetimes agree with the experimental time-of-flight data of Peterson and Moseley and of Holland and Maier within the stated experimental error bars.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452835
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Small Al clusters. II. Structure and binding in Aln (n=2–6, 13) (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 2205-2213 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The structure and stability of aluminum clusters containing up to six atoms have been studied using correlated wave functions and extended basis sets. The lowest energy structure is planar for Al4 and Al5, but three dimensional for Al6. The icosahedral, hcp, fcc, and two planar structures of Al13 were considered at the SCF level. The lowest energy structure is the icosahedron, but the planar structures are fairly low lying even in this case. A simplified description using two- and three-body interaction potentials is found to agree well with the ab initio structures and binding energies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453147
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Small Al clusters. I. The effect of basis set and correlation on the geometry of small Al clusters (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 2198-2204 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The effect of basis set and correlation on the bond length and atomization energy of Al2 and Al4 are studied. For Al13 the effect of basis set improvements is investigated only at the SCF level. A large valence basis set, such as a triple-zeta contraction of the Huzinaga (12s9p) primitive set, is needed to avoid significant superposition error and a poor description of the bonding. An ECP is developed from the Huzinaga basis, which accurately reproduces the all-electron results. It is also shown that an ECP developed from a (10s6p) primitive set reproduces the all-electron results in the same basis, but is in poor agreement with the ECP and all-electron results based upon the larger (12s9p) primitive set; this has implications on how ECP basis sets should be developed for the second row atoms. The d functions are found to be important for all clusters considered. At the SCF level, the addition of d polarization functions results in a sizable (about 0.2 a0) contraction of the Al–Al bond length and increases the dissociation energy per atom by about 0.25 eV. The inclusion of electron correlation results in a small bond contraction, but a large increase in the De per atom. The increase in De and reduction in re with the inclusion of electron correlation is almost independent of the number of d functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453146
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The bonding in FeN2, FeCO, and Fe2N2: Model systems for side-on bonding of CO and N2 (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 2129-2137 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: CO and N2 side-on bonding to one Fe atom are found to be very similar in many respects. In both cases the bonding leads to an increase in the CO or N2 bond length and a decrease in the vibrational frequency. The CO or N2 stretching modes lead to a large dipole derivative along the metal–ligand bond axis. The populations show an almost identical, large donation from the Fe 3d orbitals into the CO or N2 π*. For FeN2, the shift in the observed N2 frequency is smaller than observed for the α state of N2/Fe(111). The shift in the N2 vibrational frequency is found to increase when the N2 interacts with two Fe atoms, either at the Fe–Fe nearest neighbor distance or at the first layer Fe–Fe distance, when the side-on N2 axis is oriented perpendicular to an Fe–Fe bond. The very large shifts in the N2 ωe are similar to those observed in experiment. When the N2 and Fe2 bond axes are parallel, the N2 vibrational frequency is similar to that found for the interaction with one Fe atom. The Fe2N2 calculations yield two different low-lying Fe occupations; in one, the two Fe atoms have occupation 3d74s1 while in the second, 4s promotion to 3d mixes in the occupation 3d8 and a larger charge transfer from Fe to N2 is observed. This might be of importance for breaking the N–N bond on an Fe surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453137
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Accurate ab initio calculations which demonstrate a 3Πu ground state for Al2 (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 7007-7012 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The spectroscopic parameters and separations between the three low-lying X 3Πu, A 3Σ−g, and a 1Σ+g states of Al2 are studied as a function of both the one-particle and n-particle basis sets. Approximate correlation treatments are calibrated against full CI calculations correlating the six valence electrons in a double-zeta plus two d-function basis set. Since the CASSCF/MRCI 3Πu–3Σ−g separation is in excellent agreement with the FCI value, the MRCI calculations were carried out in an extended (20s13p6d4f)/[6s5p3d2f] Gaussian basis. Including a small correction for relativistic effects, our best estimate is that the 3Σ−g state lies 174 cm−1 above the 3Πu ground state. The 1Σ+g state lies at least 2000 cm−1 higher in energy. At the CPF level, inclusion of 2s and 2p correlation has little effect on De, reduces Te by only 26 cm−1, and shortens the bond lengths by about 0.02 a0. Further strong support for a 3Πu ground state comes from the experimental absorption spectra, since both observed transitions can be convincingly assigned as 3Πu→3Πg. The (2)3Πg state is observed to be sensitive to the level of correlation treatment, and to have its minimum shifted to shorter r values, such that the strongest experimental absorption peak probably corresponds to the 0→2 transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452349
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Full CI studies of the collinear transition state for the reaction F+H2→HF+H (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 858-861 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have performed full CI calculations on the collinear transition state for the reaction F+H2→HF+H. The full CI results are compared with those obtained from single reference and multireference CI calculations and from single reference CPF calculations. In general, only those methods which attempt to account for the effects of higher excitations, such as CPF or CI plus the Davidson correction, yield a transition state location and barrier height in good agreement with the full CI. In an extended basis, the effect of higher excitations is estimated to lower the barrier by as much as 1.5 kcal/mol; such an effect would essentially eliminate the present discrepancy between theory and experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452286
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Ab initio study on (C5H5V)2C8H8 (1987)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 109 (1987), S. 2046-2049 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00241a022
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    On the 1A1–3B1 separation in CH2 and SiH2 (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 387-391 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have determined the 1A1–3B1 separation (Te) in both CH2 and SiH2 using very large Gaussian basis sets (including g functions) and second-order CI wave functions. Complete geometry optimizations have been performed, and relativistic effects have been included using first-order perturbation theory. This treatment yields Te values for the 1A1–3B1 separation of 9.07 kcal/mol in CH2 and −20.58 kcal/mol in SiH2. Using a combination of theoretical and experimental values to estimate the contribution of zero-point vibration to the separation yields T0 values of 8.9 kcal/mol for CH2 and −20.9 kcal/mol for SiH2, in excellent agreement with the experimental values of 9.02 and −21.0 kcal/mol. A corollary to the small zero-point vibrational contribution to the separation is that the symmetric stretching fundamental in CH2(3B1) must be near 3100 cm−1, much less than a recently suggested value of around 3400 cm−1. Our accurate Te value for SiH2 establishes the ionization potential of the 1A1 state as 9.15 eV, the higher of two recent experimental values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453738
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Theoretical study of the dipole moment function of OH(X 2Π) (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 6992-6999 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The convergence of the electric dipole moment function for the X 2Π state of OH is studied as a function of extensions of both the one-particle and n-particle basis sets. Full configuration-interaction (FCI) energies and dipole moments in both [4s3p1d/2s1p] and [4s3p2d/2s1p] Gaussian basis sets are used for the calibration of a variety of approximate methods of including electron correlation. A CASSCF/MRSDCI treatment, which accurately reproduces the FCI potential and dipole moment function, is then performed in an extended [6s5p4d2f1g/4s3p2d] one-particle basis set. The dipole moment is evaluated both as an expectation value and as an energy derivative. The energy derivative is found to be generally superior, especially for the coupled pair functional approaches. Our best dipole moment function gives a permanent dipole moment within 0.01 D of experiment for v=0, and within 10% of the accurate experimental value for the difference in dipole moments between v=0 and v=1. However, our theoretical value for v=2 does not lie within the experimental error bounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452347
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Theoretical spectroscopic parameters for the low-lying states of the second-row transition metal hydrides (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 268-278 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Spectroscopic parameters (De,re,μe) are determined for the second-row transition metal hydrides using large valence basis sets in conjunction with relativistic effective core potentials (RECPs). All-electron calculations are also performed for YH and AgH to calibrate the RECP results. Electron correlation is incorporated using singles-plus-doubles configuration interaction (SDCI), the coupled pair functional (CPF) method, and a modified version (MCPF) of CPF. Although similarities exist between the bonding in the first- and second-row transition metal hydrides, the greater overlap of the d orbitals in the second row with the hydrogen 1s orbital, tends to lead to larger dissociation energies and some changes in the relative ordering of the states. For example, the ground state of ZrH is predicted to be a 2Δ state whose bonding involves 4d–5s hybrid orbitals, whereas in TiH the ground state is a 4Φ state with primarily 4s–1s bonding. The bonding in the second-row transition metal hydrides involves a mixture of all three atomic asymptotes, 4dn5s2, 4dn+15s1, and 4dn+2, whereas contribution from the 3dn+2 asymptote is unimportant in the first-row TM hydrides. However, the bonding is generally much simpler to describe in the second-row as compared with the first-row TM hydrides, and the spectroscopic parameters are much less sensitive to the level of correlation treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452617
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...