Ab initio calculation of force constants and equilibrium geometries |
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Authors: | P. Pulay |
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Affiliation: | Hungarian Academy of Sciences, Research Group for Inorganic Chemistry , Budapest |
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Abstract: | Force constants of the molecules HF, NH3, CH4 and BH4 - have been calculated ab initio by the force method with a 73/3 + 1 gaussian lobe basis set. The results, including a former calculation on H2O, agree well with experiment: the average relative error is 12 per cent for the diagonal force constants and the average absolute error is 0·06 mdyn/Å for the off-diagonal ones. The trends are also correctly reproduced. It is concluded that ab initio calculations of this accuracy can help to solve a number of spectroscopic problems. Force constants of BH4 - have been determined from a combination of spectroscopic and ab initio information. Geometries have been obtained with little computing work and show good agreement with experiment. |
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