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|Title: ||Abinitio study of the structure, infrared-spectra, and heat of formation of c4|
|Authors: ||MARTIN, Jan|
|Issue Date: ||1991|
|Publisher: ||AMER INST PHYSICS|
|Citation: ||JOURNAL OF CHEMICAL PHYSICS, 94(5). p. 3753-3761|
|Abstract: ||The lowest-lying 1A(g) and 3-SIGMA-g- states of C4 have been studied using basis sets including f functions, quadratic configuration interaction, and full fourth-order Moller-Plesset perturbation theory with multiple spin projection. Basis set effects on the linear-cyclic separation have been found to be fairly significant. Use of the 6-311G* and [5s3p1d] basis sets leads to qualitatively different conclusions; this problem is remedied by expansion of the polarization space. At the highest level of theory considered, the cyclic structure lies about 1 kcal/mol below the linear structure. A G1-type estimate of its heat of formation at 0 K of 249.6 kcal/mol is proposed. This value is in disagreement with the generally quoted experimental values, but in good agreement with third-law values by Drowart et al. [J. Chem. Phys. 31, 1131 (1959)] corrected for improved partition functions. Geometries and harmonic frequencies are reported. It is tentatively suggested that a matrix ir band at 1284 cm-1 may belong to cyclic C4; to aid experimentalists in confirming or rejecting this assignment, theoretical isotope shifts are reported.|
|Notes: ||LIMBURGS UNIV CENTRUM,DEPT SBM,B-3610 DIEPENBEEK,BELGIUM.MARTIN, JML, UNIV INSTELLING ANTWERP,INST MAT SCI,DEPT CHEM,UNIV PLEIN 1,B-2610 WILRIJK,BELGIUM.|
|ISI #: ||A1991FA77800052|
|Type: ||Journal Contribution|
|Appears in Collections: ||Research publications|
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