Table 3. Values of Total Energy and Normal Vibrations Calculated by the DFT Method for Complexes of the Silica Surface with a Neutral Molecule and an Anion of Pentanoic Acid, which Are Different in Nature, See Figures 8 and 9a.
| structure | acid molecule state | functional | total energy (Etot), au | frequency, cm–1 | IR intensity, (km/mol) |
|---|---|---|---|---|---|
| A1* | anion | B3LYP | –2489.834440 | 1620 | 853.49 |
| wB97XD | –2489.328791 | 1683 | 543.45 | ||
| M062X | –2489.236709 | 1697 | 560.08 | ||
| A2 | neutral | B3LYP | –2490.347200 | 1775 | 414.35 |
| wB97XD | –2489.831432 | 1815 | 449.48 | ||
| M062X | –2489.735112 | 1817 | 367.45 | ||
| A3 | neutral | B3LYP | –2490.347263 | 1769 | 404.37 |
| wB97XD | –2489.829392 | 1811 | 328.21 | ||
| M062X | –2489.737514 | 1823 | 335.74 | ||
| A4 | neutral | B3LYP | –2490.341615 | 1768 | 311.33 |
| wB97XD | –2489.830188 | 1815 | 327.57 | ||
| M062X | –2489.728803 | 1828 | 324.86 | ||
| A5 | neutral | B3LYP | –2490.345190 | 1756 | 316.68 |
| wB97XD | –2489.827023 | 1800 | 336.59 | ||
| M062X | –2489.727780 | 1817 | 343.18 | ||
| A6 | anion | B3LYP | –2489.847899 | 1595 | 653.78 |
| wB97XD | –2489.332636 | 1656 | 678.70 | ||
| M062X | –2489.236515 | 1660 | 654.12 | ||
| A7 | neutral | B3LYP | –2490.338512 | 1725 | 567.37 |
| wB97XD | –2489.825515 | 1771 | 569.46 | ||
| M062X | –2489.728725 | 1780 | 583.77 | ||
| A8 | anion (pentacoordinate Si) | B3LYP | –2489.824059 | 1688 | 402.06 |
| wB97XD | –2489.312576 | 1743 | 392.33 | ||
| M062X | –2489.227235 | 1753 | 376.40 | ||
| A9 | anion (pentacoordinate Si) | B3LYP | –2489.828675 | 1653 | 364.84 |
| wB97XD | –2489.314982 | 1707 | 394.75 | ||
| M062X | –2489.229216 | 1717 | 391.56 | ||
| A10 | neutral (pentacoordinate Si) | B3LYP | –2490.327281 | 1725 | 606.97 |
| wB97XD | –2489.817746 | 1763 | 617.02 | ||
| M062X | –2489.726480 | 1768 | 669.66 | ||
| B1** | anion (pentacoordinate Si) | B3LYP | –4174.238445 | 1661 | 522.59 |
| wB97XD | –4173.475992 | 1716 | 523.87 | ||
| M062X | –4173.407924 | 1684 | 591.30 | ||
| B2 | anion (pentacoordinate Si) | B3LYP | –4174.239087 | 1669 | 424.45 |
| wB97XD | –4173.476429 | 1718 | 433.03 | ||
| M062X | –4173.408024 | 1690 | 500.60 | ||
| B3 | anion | B3LYP | –4174.255982 | 1615 | 910.04 |
| wB97XD | –4173.484618 | 1671 | 866.49 | ||
| M062X | –4173.405767 | 1650 | 1102.22 | ||
| B4 | neutral | B3LYP | –4174.760011 | 1769 | 494.35 |
| wB97XD | –4173.993678 | 1810 | 443.49 | ||
| M062X | –4173.908980 | 1828 | 564.18 | ||
| B5 | anion (pentacoordinate Si) | B3LYP | –4174.247630 | 1652 | 428.52 |
| wB97XD | –4173.484559 | 1709 | 462.03 | ||
| M062X | –4173.413773 | 1721 | 474.98 | ||
| B6 | neutral | B3LYP | –4174.756579 | 1757 | 317.00 |
| wB97XD | –4173.987810 | 1803 | 334.50 | ||
| M062X | –4173.904618 | 1817 | 340.18 | ||
| B7 | neutral | B3LYP | –4174.759136 | 1769 | 469.31 |
| wB97XD | –4173.996225 | 1795 | 377.56 | ||
| M062X | –4173.910895 | 1813 | 401.69 | ||
| C1*** | anion | M062X | –6756.344541 | 1632 | 645.66 |
| C2 | anion (pentacoordinate Si) | M062X | –6756.355978 | 1718 | 469.13 |
a
Only the values of the frequencies of highly characteristic oscillations where the carboxyl group of pentanoic acid or its anion participates are given. Frequencies were scaled by 1.0. *, Structures of the A series refer to the “soft” surface model. **, B series structures refer to the “hard” surface model. ***, C series structures refer to the extended “hard” surface model (Figure 9).