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. Author manuscript; available in PMC: 2010 Jan 1.
Published in final edited form as: J Chem Theory Comput. 2009;5(6):1680–1691. doi: 10.1021/ct900079t

Table 3.

Partial charge assignments from various charge optimization schemes and their respective molecular propertiesa.

Charging schemes
Benzene Substituent Atomname/ Targets Initial CHELPG2 CHopt2 CHELPG4 CHopt4 Control
Y=SCH3 Charges: CA 0.220 0.206 0.039 0.218 0.291 0.468
S −0.390 −0.305 −0.186 −0.292 −0.292 −0.432
CT3 −0.100 −0.005 −0.122 0.007 −0.110 −0.305
HA 0.090 0.035 0.090 0.046 0.090 0.090
CA −0.115 −0.115 −0.115 −0.185 −0.214 −0.115
HP 0.115 0.115 0.115 0.150 0.134 −0.115
ΔΔGhydr −1.83 (expt) −3.27 −1.20 −1.37 −1.86 −1.80 −5.46
μx −0.04 (HF) −1.42 −1.76 −0.03 −0.65 −0.11 −4.29
μy 1.72 (HF) 2.34 1.52 1.74 1.70 1.93 1.35
Y=CN Charges: CA 0.130 0.097 0.425 0.084 0.132 −0.475
CN 0.400 0.370 −0.238 0.357 0.308 −0.451
NC −0.530 −0.467 −0.187 −0.480 −0.440 0.024
CA −0.115 −0.115 −0.115 −0.124 −0.019 −0.115
HP 0.115 0.115 0.115 0.143 0.308 0.115
ΔΔGhydr −2.66 (expt) −5.30 −3.70 −3.04 −4.47 −3.70 −5.53
μx −5.84 (HF) −4.49 −3.90 −4.58 −4.13 −2.80 2.82
Y=CHO Charges: CA 0.120 0.051 0.252 0.055 0.177 −0.264
CD 0.160 0.465 −0.017 0.469 0.099 0.581
O −0.330 −0.536 −0.332 −0.531 −0.378 −0.530
HR1 0.050 0.021 0.098 0.025 0.092 0.213
CA −0.115 −0.115 −0.115 −0.152 −0.016 −0.115
HP 0.115 0.115 0.115 0.142 0.022 0.115
ΔΔGhydr −3.18 (expt) −1.98 −5.63 −3.31 −5.83 −3.30 −11.39
μx 3.19 (HF) 2.28 3.16 2.68 3.09 2.92 3.53
μy −3.05 (HF) −2.02 −2.11 −2.80 −1.78 −3.01 0.71
Y=OCH3 Charges: CA 0.220 0.458 −0.022 0.513 0.318 0.020
O −0.390 −0.515 −0.093 −0.460 −0.290 −0.503
CT3 −0.100 0.148 −0.155 0.203 −0.065 0.213
HA 0.090 −0.030b 0.090 0.025 0.090 0.09
CA −0.115 −0.115 −0.115 −0.326 −0.135 −0.115
HP 0.115 0.115 0.115 0.160 0.019 0.115
ΔΔGhydr −0.20 (expt) −1.92 −2.43 −0.57 −2.17 −0.43 −7.73
μx 0.68 (HF) −0.75 −3.26 0.49 1.07 0.53 2.02
μy 1.53 (HF) 1.64 1.15 0.93 1.57 1.48 2.71
a

Experimental hydration free energies (ΔΔGhydr) relative to benzene in kcal/mol taken from ref 40. Computed relative hydration free energies are approximated from the difference between GBMV and vacuum energy-minimized energies. Dipole moments are reported in units of Debye from the standard Gaussian 03 orientation and their HF/6-31+G* values have been scaled by 15%.

b

The negative charges assigned to the methyoxy hydrogen atoms are a result of the offset factor used to require that the overall charge of the re-assigned atoms sums to zero.