|Quantum Chemistry Laboratory|
|Prof. N. Rösch|
Construct a Z-Matrix for methane, CH4 (Td). Use the experimental C-H distance, 1.085 Å , and the tetrahedral angle, about 109.47122°. This value is precise enough so that the program Gaussian will replace it by the exact value. If the value is less accurate, Gaussian will not recognize the tetrahedral angle and will thus break the tetrahedral symmetry.
As in Exercise 2 the Z-matrix has to preserve the symmetry of the molecule during geometry optimization.
The high tetrahedral symmetry of the methane molecule may pose a challenge for the novice. Therefore the first level of solution to this exercise contains several hints for setting up the Z-matrix.
|||D. L. Gray and A. G. Robiette, "The anharmonic force field and equilibrium structure of methane", Mol. Phys. 37 (1979) 1901.|
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