Utilização do software livre orca para obtenção de espectros de infravermelho de monoterpenóides

Abstract

The present work aims to analyze the free software ORCA, a calculation program that involves quantum chemistry, and with that to compute several properties of molecules. One of the possible functions is to produce infrared spectra. This is a method used to identify certain structures present in molecules, such as indicating organic functions, such as hydroxyls and carbonyls, for example. For this, the group of monoterpenes was chosen to test the program, molecules that are generally found in natural products, composed of ten carbon atoms and that present many variations, being relatively quick to simulate and that present differences between them that can be observed. As this group is quite large, with thousands of molecules, fifteen of them were selected. It is also important to mention Avogadro, free software for computational modeling of molecules responsible for designing them to be simulated and for later reading the processed data by plotting the spectra. Therefore, it was possible to verify the ability of ORCA to calculate spectra, since when ready, they would be compared to results obtained experimentally in laboratories from a database (from the Japanese Spectral Database for Organic Compounds). Therefore, aspects such as the accuracy of the wave number found, more characteristic features of the bands related to certain parts of the molecules and their intensity can be verified. The use of the program is very advantageous, since it is free software, which can be used in Windows or Linux and presents good results, plotting spectra that show the main bands related to the functions of the molecules used, whose error, compared with experimental results, is quite low, which demonstrates good accuracy in the results. There is still the benefit that a computer is less valuable than laboratory equipment and can be used for many other functions. Thus, it is expected that this work can contribute significantly to the study of infrared spectrometry, by offering an alternative to the uses of spectrophotometers, which are usually more expensive and difficult to access than computers.