IR Spectrum Prediction Service

Infrared spectroscopy is the ability of molecules to selectively absorb certain wavelengths of infrared rays, causing the transition of vibrational and rotational energy levels in the molecule. The infrared absorption spectrum of the substance can be obtained by detecting the absorption of infrared rays. It is also called molecular vibrational spectroscopy or vibrational rotation spectrum. The position and intensity of the infrared absorption peak reflect the characteristics of the molecular structure, which can be used to identify the structural composition of the unknown or determine its chemical group; and the absorption intensity of the absorption band is related to the content of the chemical group and can be used for quantification analysis and purity identification. In addition, infrared spectroscopy has also played a certain role in the study of the mechanism of chemical reactions.

IR spectrum. Figure 1. IR spectrum.

Overall solutions

MedAI provides you with professional quantum chemistry methods to calculate the infrared spectra of compounds. Because the potential energy of a molecule is a function of the coordinates of the atoms in the molecule, it changes with the relative position of the atoms. The vibration in the IR spectrum can be expressed by the change of the relative position of the atoms in the molecule, and the potential energy gradient with the change of the relative position of the atoms is equivalent to the restoring force in the vibration. After optimizing the geometric configuration of the molecule, MedAI differentiates its molecular coordinates according to the normal vibration mode to obtain the differential value of the molecular energy change, and then calculates the force constant of each normal vibration mode, so as to calculate the molecular vibration The energy level difference of the equivalent harmonic oscillator and thus the position of the IR spectrum band.

Services items

Project name IR Spectrum Prediction Service
Our services
  • MedAI uses ChemBioOffice to optimize the molecular structure at the MNDO, AM1, and PM3 levels and the Gaussian 09 program package at the B3LYP/6-31G(d) level to obtain a balanced geometric structure. On this basis, the molecular vibration frequency is calculated using the same theoretical level.
  • On the basis of structural optimization, the vibrational spectra of benzene molecules are calculated using the same theoretical level. Only the vibration mode accompanying the change of the dipole moment in vibration has infrared absorption, that is, it has infrared activity.
  • Using Gaussian 09 to use high-level quantum chemistry methods to predict infrared spectroscopy (IR) of small molecule systems, post-consistent field (post-HF) methods include MP2, MP3, MP4, CCSD, CCSD (T) and MC-SCF, etc., which can give a precise infrared spectrum.
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