In order to study the electronic structure and the variation of chemical shift of the 181Ta nuclei in ternary A3BC4 semiconductor, the first-principles calculations are used by PBE-GGA, BJ, and TB-mBJ functionals. By comparing these three kinds of functionals, the results of TB-mBJ are more in line with the experimental values. The electronic structure calculated by TB-mBJ functional shows that TaCu3X4 (X = S, Se, Te) are indirect bandgap semiconductors and TaTl3X4 (X = S, Se) are direct bandgap semiconductors. By decomposing the chemical shifts contributed by the different orbitals, we found that the chemical shifts are related to the electronic structure. In this paper, the variation (up to 2500 ppm) of NMR chemical shift of 181Ta nuclei is related to the d orbital of Ta.
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