Paper
28 January 1987 Molecular Orbital And X-Ray Diffraction Studies Of Nonlinear Optictl And Structural Properties Of 5-Nitrouraci1
Brian M Pierce, Richard M Wing
Author Affiliations +
Abstract
Previous nonlinear optical measurements J.G. Bergman, G.R. Crane and B.F. Levine, Appl. Phys. Lett. 20.21 (1972)] show 5- nitrourecil(5NU) to be phase matchable with a coefficient for second-harmonic generation equal approximately to that for Li103 [d36(5NU) = (1.0 ± 0.1)(133( Li103)]. The X-ray crystal structure determination shows 5NU to crystallize in the orthorhombic space group P212121 containing 4 molecules per unit cell of dimensions a = 9.936 ± 0.001 Å, b = 10.355 t 0.001 Å and c = 5.462 ± 0.002 Å. The origin of the excellent structural properties of 5NU is an extensive hydrogen bonding network in the crystal. The orientations of the 4 molecules in the unit cell are such that the unit cell has no net dipole moment. The magnitudes of the ground state dipole moments calculated for isolated 5NU are 6.09 D (INDO-SC1), 6.21 D (INDO-SDC1) and 6.30 D initio-4-31G). The 1.ππ and charge-transfer (CT) excited states of 5NU are calculated to define the second-order nonlinear optical properties of the molecule. The l mu* states of 5NU are calculated to contribute very little to these properties. The level of treatment of electron correlation in the molecular orbital ( MO) procedures is found to have a marked effect on the calculations of the excited electronic state and second-order nonlinear optical properties of 5NU. The INDO-SDCI MO procedure, with its extensive treatment of electron correlation, calculates a value of d36 1.2)1:133( Li103) for isolated 5NU that is very close to the measured value cited above. A preliminary bonding electron density distribution map for 5NU is presented.
© (1987) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Brian M Pierce and Richard M Wing "Molecular Orbital And X-Ray Diffraction Studies Of Nonlinear Optictl And Structural Properties Of 5-Nitrouraci1", Proc. SPIE 0682, Molecular and Polymeric Optoelectronic Materials, (28 January 1987); https://doi.org/10.1117/12.939634
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KEYWORDS
Crystals

Chemical species

Nonlinear crystals

Molecules

Molybdenum

X-ray diffraction

Hydrogen

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