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. 2013 Dec 23;118(3):833–844. doi: 10.1021/jp409652k

Table 4. Fractional populations of QSin Groups derived by MD simulations and NMRa.

  xPn populationsb
 xSin populationsb
 silicate network connectivity
label QP0 QP1 QSi1 QSi2 QSi3 QSi4 N̅BOSi(nom) N̅BOSi(NMRP)c N̅BOSi(NMRSi)d N̅BOSi(MD)e
BG2.6(2.1) 0.834 (0.959) 0.166 (0.041) 0.186 (0.066) 0.517 (0.724) 0.266 (0.210) 0.021 (0.000) 2.11 2.11 2.14 2.10
BG6.0(2.1) 0.798 (0.955) 0.200 (0.045) 0.197 (0.056) 0.514 (0.658) 0.252 (0.286) 0.027 (0.000) 2.15 2.14 2.20 2.09
                     
BG0(2.5) – – 0.068 (0.015) 0.428 (0.409) 0.425 (0.555) 0.076 (0.021) 2.50 2.50 2.58 2.50
BG1.0(2.5) 0.670 (0.899) 0.318 (0.101) 0.073 (0.017) 0.426 (0.455) 0.435 (0.512) 0.065 (0.016) 2.50 2.50 2.53 2.49
BG2.0(2.5) 0.721 (0.896) 0.267 (0.104) 0.080 (0.012) 0.418 (0.405) 0.440 (0.563) 0.060 (0.020) 2.50 2.50 2.59 2.48
BG4.0(2.5) 0.622 (0.931) 0.364 (0.069) 0.084 (0.010) 0.443 (0.372) 0.409 (0.598) 0.063 (0.020) 2.50 2.49 2.63 2.45
BG6.0(2.5) 0.690 (0.902) 0.304 (0.098) 0.087 (0.010) 0.457 (0.423) 0.392 (0.551) 0.062 (0.016) 2.50 2.48 2.57 2.42
                     
BG2.6(2.7) 0.517 (0.838) 0.475 (0.162) 0.041 (0.006) 0.336 (0.242) 0.507 (0.677) 0.115 (0.075) 2.74 2.73 2.82 2.70
                     
BG0(2.9) – – 0.016 (0.000) 0.225 (0.094) 0.571 (0.793) 0.189 (0.113) 2.93 2.93 3.02 2.93
BG2.0(2.9) 0.417 (0.795) 0.553 (0.205) 0.017 (0.000) 0.246 (0.108) 0.553 (0.791) 0.183 (0.101) 2.93 2.92 2.99 2.90
BG3.0(2.9) 0.444 (0.814) 0.528 (0.186) 0.020 (0.000) 0.252 (0.144) 0.562 (0.779) 0.166 (0.077) 2.93 2.91 2.93 2.87
BG4.0(2.9) 0.440 (0.805) 0.554 (0.195) 0.022 (0.000) 0.269 (0.118) 0.539 (0.791) 0.169 (0.091) 2.93 2.90 2.97 2.86
BG6.0(2.9) 0.460 (0.821) 0.527 (0.179) 0.028 (0.000) 0.295 (0.121) 0.529 (0.778) 0.149 (0.101) 2.93 2.89 2.98 2.79
a

Values within parentheses correspond to the populations obtained by NMR. Typical standard deviations of the MD-generated xPn and xSi populations are σ = 0.034 and σ = 0.011, respectively, as estimated from all simulations that involved ≈6000 atoms (see the Supporting Information).

b

The MD-derived structures also comprise minor amounts of QP2 (xP ≲ 0.03) and QSi0 (xSi ≲ 0.01) groups that are not listed.

c

Corrected for the NMR-derived minor QP1 contributions.

d

Obtained from the 29Si NMR-derived {xSin} sets via eq 3.

e

Obtained from the MD data.