Ab initio calculations of [formula omitted]Si solid state NMR chemical shifts of silane and silanol groups in silica

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We report the results of first principles density functional theory (DFT) calculations on the 1 H and 29 Si NMR chemical shifts of silane and hydroxyl groups in silica. The structure of the isolated ≡Si–H and ≡Si–OH or of the geminal =Si(H) 2 and =Si(OH) 2 defects has been fully optimized from mechanically embedded cluster models derived from crystalline α-quartz and the nuclear magnetic shielding properties have been determined according to the GIAO method. The computed 29 Si chemical shifts, δ( 29 Si) in ppm, are (in parenthesis the experimental values): ≡Si–OH −99 (−99), ≡Si–H −86 (−85), =Si(OH) 2 −85 (−89), =Si–(H) 2 −55 (−50).