3.3 Quantum chemical calculations

To compare the results obtained by our empirical relationship with those obtained by quantum chemistry methods, we have calculated vibrational zero-point


### Vibrational Zero-Point Energy of Organosilicon Compounds DOI: http://dx.doi.org/10.5772/intechopen.87021

mean error to 1.68 (4.0%) if the intercept is different from 0 (b 6¼ 0) to 2.28 (7.0%) if b = 0. These results are slightly less good than those obtained by our approach.

Bond Bond contribution (BCi) Ref. C—H 7.5877 [38] N—H 7.2013 [38] O—H 7.2964 [38] S—H 5.6921 [38] C—O 2.6985 [38] C—C 2.0751 [38] C—N 4.1409 [38] C—S 1.4403 [38] N—N 6.8372 [38] C—F 3.3078 [38] C—Cl 2.2051 [38] C=C 2.6501 [38] C=N 3.8852 [38] C=O 3.9343 [38] C=S 2.7319 [38] C☰C 4.4125 [38] C☰N 4.8169 [38] C—Br 1.9837 [39] Si—H 5.8011 [49] Si—C 0.3593 [49] Si—Cl 1.7690 [49] Si—O 1.3335 [49] Si—Si �1.4548 [49] P—H 6.6486 [29] P—C 1.4190 [29] P—O 1.8406 [29] P—Cl 1.6717 [29] P—N 0.9873 [29] P—F 2.1507 [29] P—S 1.5424 [29] P=O 2.4032 [40] P=S 0.6131 [40]

Modern Spectroscopic Techniques and Applications

To compare the results obtained by our empirical relationship with those obtained by quantum chemistry methods, we have calculated vibrational zero-point

3.3 Quantum chemical calculations

Bond contributions to ZPE (in kcal/mol).

Table 1.

44
