Digital Twins Solve the Mystery of Raman Spectra of Parental and Reduced Graphene Oxides

Abstract

Digital Twins concept presents a new trend in virtual material science, common to all computational techniques. Digital twins, virtual devices and intellectual products, presenting the main constituents of the concept, are considered in detail on the example of a complex problem, which concerns an amazing identity of the D-G-doublet Raman spectra of parental and reduced graphene oxides. Digital twins, presenting different aspects of the GO and rGO structure and properties, were virtually synthesized using a spin-density algorithm emerging from the Hartree-Fock approximation. Virtual device presents AM1 version of the semi-empirical unrestricted HF approximation. The equilibrium structure of the twins as well as virtual one-phonon harmonic spectra of IR absorption and Raman scattering constitute a set of intellectual products. It was established that in both cases the D-G doublets owe their origin to the sp3 and sp2 C-C stretchings, respectively. This outwardly similar community reveals different grounds. Thus, multilayer packing of individual rGO molecules in stacks provides the existence of the sp3 D band in addition to sp2 G one. The latter is related to stretchings of the main pool of sp2 C-C bonds, while the sp3 constituent presents out-of-plane stretchings of dynamically stimulated interlayer bonds. In the GO case, the sp3 D component, corresponding to stretchings of the main pool of sp3 C-C bonds, is accompanied by an sp2 G component, which is related to stretchings of the remaining sp2 C-C bonds provided with the spin-influenced prohibition of the 100% oxidative reaction in graphene domain basal plane.