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
  • 11
    Electronic Resource
    Electronic Resource
    A reanalysis of the molecular beam electric resonance Stark effect data for the a 3Π state of carbon monoxide (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 2781-2788 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The highly precise measurements of Stark coefficients in the lambda doubling transitions of a 3Π CO obtained in previously published molecular beam electric resonance experiments have been reanalyzed. Certain perturbations between vibrational levels of the a 3Π and a' 3Σ+ states that were neglected in the earlier treatment have been found to be important. An apparent error, by a factor of in the Stark matrix elements that were used in prior work, has also been corrected. The previously reported experimental determination of the dipole moment function of a 3Π CO is shown to be invalid. Thus, the relatively flat appearance of the dipole moment function found in previous ab initio studies may indeed be correct. The dipole moment in the a' 3Σ+ state and the transition moment between the a 3Π and a' 3Σ+ states are substantially revised to −0.79 and +0.64 D, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455031
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Spectroscopic constants and dipole moment functions of the 22 electron dications SiNe++, PF++, SO++, NCl++, and CAr++ (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 3528-3535 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The potential energy functions and spectroscopic constants of a series of eighteen 22 electron diatomic molecules with charge −1, 0, +1, and +2 have been obtained using version 1 of the coupled electron pair approximation (CEPA-1) with a Gaussian basis set of 101 functions, containing both f orbitals and diffuse s and p orbitals. All of these except the negative ions have also been treated by singles and doubles configuration interaction (CI-SD) and by the latter including a size consistency correction [CI-SD(s)] with a slightly smaller basis set (93 functions) that omitted the diffuse s and p functions. Both methods [CEPA-1 and CI-SD(s)] produce values of re and ωe for the neutral and monocation species that give deviations from experiment that are both small and smoothly varying across the series. Corrections based on these deviations have been applied to the re and ωe values of the spectroscopically unknown dications, SiNe++, PF++, SO++, NCl++, and CAr++, which possess either great kinetic stability, or in some cases, even thermodynamic stability, as published ab initio calculations have already demonstrated. Our estimated uncertainties for the corrected re and ωe values are different for the five dications, depending upon the available spectroscopically known comparison species and the consistency achieved between methods, but in the most favorable case (PF++) they are ±0.002 A(ring) and ±10 cm−1. The dipole moment functions of the doubly charged ions have been calculated for the first time (using CI-SD) and used to estimate the intensities of the rotational and vibrational spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460855
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Theoretical dipole moment functions involving the a 3Π and a' 3Σ+ states of carbon monoxide (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 5029-5036 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Potential energy and dipole moment functions have been calculated for the first two excited electronic states of CO by several ab initio methods using large Gaussian basis sets. Similar calculations on the ground state have also been performed to provide a basis for comparison. The types of calculations on the a 3Π state included complete active space self-consistent field (CASSCF), single reference single and doubles configuration interaction (CI-SD) including a size consistency correction [CI-SD(s)], quadratic CI-SD (QCI-SD), and quadratic CI-SD including the effects of triple excitations [QCI-SD(T)], and version 1 of the coupled electron pair approximation (CEPA-1).The best calculated dipole moment functions for the a 3Π state have been found to be consistent with earlier theoretical results with respect to shape (slope, μ'e), and also more accurate in predicting the equilibrium value μe. Theoretical dipole moment functions for the a' 3Σ+state are presented for the first time, at the CI-SD, CI-SD(s), and CASSCF levels of approximation. The first two of these yield estimates of μe that are in very good agreement with that derived from the analysis of perturbations in the molecular beam electric resonance (MBER) Stark effect of the a 3Π state. The (a–a') electronic transition moment has also been calculated at the CASSCF and CI-SD levels. Our CASSCF value of 0.23 D (v‘=4, v'=0) compares well with values derived from the MBER Stark effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458640
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    An ab initio study of the 24 electron radicals PF, SO, NCl, SF+, ClO+, SiF−, PO−, NS−, and CCl− in their X 3∑− electronic states (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 1876-1888 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The potential energy functions (PEFs) of the X 3∑− states of PF, SO, NCl, SF+, ClO+, SiF−, PO−, NS−, and CCl− have been calculated by several ab initio methods using a basis set of 101 contracted Gaussian-type orbitals. The methods used included fourth order Møller–Plesset perturbation theory with single, double, and quadruple substitutions (MP4SDQ), singles and doubles configuration interaction (CI-SD), version 1 of the coupled electron pair approximation (CEPA-1), and complete active space self-consistent field (CASSCF). The CI-SD PEFs were very similar to those calculated by CEPA-1 when a size-consistency correction was added to the CI-SD total energies, and these results were designated CI-SD(s). The results for the neutral radicals are compared to the available experimental data, and predictions of the rotational and vibrational spectra of the ions have been made. Dissociation energies have been calculated for all nine species at the MP4SDTQ (MP4SDQ including triple substitutions) level of approximation, which also yielded MP4SDTQ ionization potentials for SF and ClO and electron affinities of SiF, PO, NS, and CCl. All of the negative ions are predicted to be stable with respect to loss of an electron by at least 20 kcal/mol. Electric dipole moment functions have also been computed for each species by CI-SD, CEPA-1, and CASSCF. Molar integrated IR absorption intensities for the fundamental transitions are predicted to be (in cm2mol−1) 15 860 (PF, CEPA-1), 1890 (SO, CASSCF), 5995 (NCl, CEPA-1), 7235 (SF+, CEPA-1), 1205 (ClO+, CASSCF), 20 070 (SiF−, CEPA-1), 20 390 (PO−, CASSCF), 90.0 (NS−, CASSCF), and 22 600 (CCl−, CEPA-1).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459065
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Predictions of the rotational and vibrational spectra of SiF+, PO+, and NS+ by Møller–Plesset perturbation theory (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 4929-4944 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In order to predict accurately the spectroscopic constants of SiF+, PO+, and NS+, calculations at the MP4SDQ level have been carried out for the following series of 22 electron diatomics: AlF, SiF+, SiO, PO+, PN, NS+, CS, CCl+, and BCl. Two basis sets, one containing 66 contracted Gaussian-type orbitals and the other with 93, have been employed for each of the nine molecules to calculate potential energy functions and spectroscopic constants. The ab initio re and ωe values for the three ions whose high resolution spectra were not previously observed were corrected by reference to deviations between theory and experiment for the other six species, whose spectra were already well known. The dipole moments and electric field gradients of each species at the equilibrium bond distance were calculated at the CI-SD level, and their dissociation energies were found to be predicted well by MP2 and very well by MP4SDTQ calculations. In order to understand better the differences between the spectral predictions of the two basis sets, re and ωe of the well known first row analogs BF, CF+, CO, NO+, and N2 were computed at the MP4SDQ level with a series of five basis sets of increasing flexibility. Using the current prediction for SiF+ we have recently located its rotational spectrum, extensive measurements of which will be published separately.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455636
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    The microwave spectrum of PO+: Comparison to SiF+ (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 3504-3510 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The microwave spectrum of PO+ has been detected in discharges in mixtures of PF3, O2, and Ar. Precise frequencies were obtained for 48 rotational transitions in the range 140–470 GHz, including all vibrational states v=0–11. Eight of the lines measured were transitions of P18O+, obtained using 18O2. To fit all of these to a mass independent Dunham expansion, a Watson ΔO01 parameter was required to describe the oxygen isotope shift. From the combined analysis a set of eight mass independent Dunham parameters Ukl and the Dunham potential constants a1–a5 were extracted. Harmonic and anharmonic vibrational constants are obtained from the microwave analysis and compare very well to published results from low resolution emission spectroscopy; the final microwave values of re and ωe are 1.424 992 7(4) A(ring) and 1411.5(3) cm−1. These and the a1–a5 coefficients are in very good agreement with the results of several ab initio calculations we have done on PO+ (and other 22 electron diatomics), including those that were used to define the limits of our initial search for the microwave spectrum of PO+. The vibrational temperature of PO+ in our magnetically enhanced negative glow discharge was found to be very high, near 5500 (500) K. Some additional observations of the microwave spectrum of SiF+, used as a probe of the dynamical and chemical behavior of SiF+ in discharges, are also reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459771
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    An ab initio investigation of the spectroscopic properties of ClF, ArF+, SF−, and ClO− in their ground electronic states (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 7412-7417 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The potential energy and electric dipole moment functions of the 26-electron species ClF, ArF+, SF−, and ClO− in their X 1∑+ electronic states have been calculated by the coupled electron pair approximation (CEPA) and singles and doubles configuration interaction (CI-SD) using a basis set of 101 contracted Gaussian-type orbitals. Potential energy functions have also been calculated by Møller–Plesset fourth-order perturbation theory with single, double, and quadruple excitations (MP4SDQ) for all four species. Values of re and ωe calculated for the ClF molecule agree with experiment to within 0.004 A(ring) and 16 cm−1, respectively, at the CEPA and MP4SDQ levels of approximation, and also when a size consistency correction was applied to the CI-SD energies [designated CI-SD(s)]. Predictions of rotational and vibrational spectra have been made for the isoelectronic ions, ArF+, SF−, and ClO−. The MP4SDTQ (MP4SDQ with the addition of triple substitutions) level of approximation was used to calculate dissociation energies for all four species and electron affinities for the radical precursors of the negative ions. From the CEPA potential energy and electric dipole moment functions, dipole moment matrix elements and infrared radiative transition probabilities have been predicted. Molar IR integrated absorption intensities for the fundamental transitions have been predicted to be 3065 cm2 mol−1 (ClF), 15 500 cm2 mol−1 (SF−), 835 cm2 mol−1 (ClO−), and 22.3 cm2 mol−1 (ArF+).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458226
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Complete active space self-consistent field potential energy surfaces, dipole moment functions, and spectroscopic properties of O3, CF2, NO−2, and NF+2 (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 414-430 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Three-dimensional potential energy and dipole moment surfaces have been calculated for the 24 electron triatomics O3, CF2, NO−2, and NF+2 using complete active space self-consistent field wave functions (CASSCF) and a basis set of 87 (99 for NO−2) contracted Gaussian-type orbitals (cGTOs). The analytical potential energy functions (PEFs) have been used in perturbation and variational calculations of anharmonic spectroscopic constants and vibrational energy levels. The results for O3 and CF2 are compared to the available experimental data, and predictions of the rotational and vibrational spectra of NO−2 and NF+2 have been made by comparison to these species. The equilibrium geometries of NO−2 and NF+2 are predicted to be re=1.260 A(ring), θe=116.5° and re=1.242 A(ring), θe=108.0°, respectively. The fundamental vibrational frequencies (ν1,ν2,ν3) and absolute band intensities (at 300 K) of these two ions are predicted to be 1286 cm−1/31 cm−2 atm−1, 782 cm−1/13 cm−2 atm−1, 1232 cm−1/2900 cm−2 atm−1 (NO−2) and 1272 cm−1/181 cm−2 atm−1, 711 cm−1/25 cm−2 atm−1, 1210 cm−1/1230 cm−2 atm−1 (NF+2). Band intensities for several low-lying vibrational transitions have been calculated for all four species from the CASSCF dipole moment functions, and comparisons to experiment have been made for O3 and CF2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460357
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Configuration interaction spectroscopic properties of X 2Σ+ HNC+ and X 2Π HCN+ (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 4946-4953 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Stretching potential energy and dipole moment functions have been calculated for the ground electronic states of the HNC+ (X 2Σ+) and HCN+ (X 2Π) radical ions by singles and doubles configuration interaction (CI-SD) with a basis set of 74 contracted Gaussian-type orbitals. By comparison to analogous calculations on the CN radical, the ground state rotational constants B0 of HNC+ and HCN+ are predicted to be 47, 122±70 MHz and 40, 185±70 MHz, respectively, by CI-SD with the addition of a size consistency correction, designated CI-SD(s). Stretching band origins and intensities have been obtained from the analytical potential energy and dipole moment functions using variational methods. The stretching fundamental band origins, ν1 and ν3, and their intensities are predicted to be 3464 cm−1/2507 cm−2 atm−1 and 2212 cm−1/2.3 cm−2 atm−1, respectively, for HNC+ and 3099 cm−1/1189 cm−2 atm−1 and 1806 cm−1/70.3 cm−2 atm−1 for HCN+. The equilibrium dipole moment of HNC+ calculated by CI-SD is just 0.66 D, while that of HCN+ is 3.63 D. In agreement with earlier studies the HNC+ isomer is predicted to be lower in energy than HCN+, and our calculated energy of isomerization, 18.91 kcal/mol, is in good agreement with this previous work. The Renner–Teller effect in the HCN+ isomer is predicted within the harmonic approximation by CI-SD(s) to be small, with the Renner parameter ε and the Renner–Teller constant εω2 being −0.056 and −39.2 cm−1, respectively (ω2=696 cm−1). Quadrupole coupling constants have also been computed for HNC+ and HCN+, as well as for the neutrals HCN and HNC. The proton affinity at zero temperature PA0 of CN is 150.6 kcal/mol by CI-SD(s), and the adiabatic ionization potentials of HNC and HCN are 273.3 and 307.7 kcal/mol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458683
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Ground state spectroscopic and thermodynamic properties of AlO−, SiN−, CP−, BS−, BO−, and CN− from Møller–Plesset perturbation theory (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 7239-7250 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Rotational and vibrational constants in the ground states of the 22 electron negative ions AlO−, SiN−, CP− and BS− and their 14 electron analogs BO− and CN− have been calculated at the MP4SDQ level with two large Gaussian basis sets. Identical calculations have also been carried out on the well known isoelectronic neutral species and used to correct the ab initio values of re and ωe of the ions. Calculations of the heavy atom distances of HCP, HBS, HBO, and HCN were performed to provide additional calibrations for the bond lengths of CP−, BS−, BO−, and CN−, respectively. Singles and doubles CI have been used to obtain equilibrium dipole moments and electric field gradients, from which quadrupole coupling constants were derived. Dissociation energies with expected accuracies of at least 5 kcal mol−1 were calculated by MP4SDTQ for the negative ions and were used to derive electron affinities for the radical precursors. Proton affinities of the negative ions and H–AB dissociation energies of the triatomic species were calculated at the MP4SDQ level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456201
    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...