Conclusion

The use of quantum chemical calculations to determine various molecular properties has become indispensable, even for "experimental" laboratories and non-specialists. This is evident in most scientific publications in the field of molecular chemistry. Computational chemistry has become an indispensable tool, and will continue to be so in the future, thanks in particular to advances in computing and the evolution of calculation techniques. The availability of easy-to-use "black box" software has greatly facilitated this state of affairs. However, a good knowledge of quantum chemistry methods is still essential to correctly interpret the results of calculations. Indeed, as explained in this article, a number of approximations are involved in these calculations, which should not be ignored at the risk of producing erroneous interpretations or predictions.