Objective: The geometrical optimization, vibrational spectrum of cyanamide in singlet, triplet and quintet state using Density functional Theory method.
Materials and Methods: The methods used here are MP2, MP3, MP4 and DFT method with different exchange and correlation functional (BLYP, B3LYP, B3PW91, PBEPBE, PBE1PBE) and different basis sets viz. 6-311G, 6-311+G, 6-311+G*, 6-311++G*, 6-311++G**, aug-cc-pvdz, aug-cc-pvtz and SDD to know at what level of theory cyanamide has the lowest energy. All the calculations are performed using Gaussian suit of program
Results: Cyanamide shows the lowest energy at B3LYP/aug-cc-pvdz level among different levels used here. The geometrical parameter and vibrational frequencies obtain at this level are in close agreement with the experimental determinations. Out of nine vibrational modes, seven modes in triplet and eight in quintet state are red shifted than those in a singlet state. The only blue shifted mode in quintet is the C-N stretching mode with a blue shifted of 220 cm-1 than that for the singlet.
Conclusion: The geometrical parameter and vibrational frequencies obtain at this level are in close agreement with the experimental determinations. The dipole moment decreases in higher spin state than the single
