COSMORS and COSMOSAC parameters¶
The COSMORS model has general parameters and element specific parameters. ADF’s COSMOSAC 2013ADF model has general parameters, but also uses some of the COSMORS parameters, such as the element specific parameters. There are also technical and accuracy parameters, such as convergence criteria. This section explains how to set these parameters, and shows the default values for these parameters. By default the COSMORS method is chosen.
COSMORS general parameters¶
CRSPARAMETERS
{RAV rav}
{APRIME aprime}
{FCORR fcorr}
{CHB chb}
{SIGMAHBOND sigmahbond}
{AEFF aeff}
{LAMBDA lambda}
{OMEGA omega}
{ETA eta}
{CHORTF chortf}
{combi1998  combi2005}
{hb_all  hb_hnof}
{hb_temp  hb_notemp}
{fast  nofast}
End
The ADF default values are optimized parameters for ADF calculations. The Klamt values can be found in Ref. 1. See also Ref. 1 for the meaning of the parameters.
symbol 
ADF Default 
ADF combi1998 
Klamt 
MOPAC PM6 

Ref. 2 
Ref. 2 
Ref. 1 

rav (\(r_{av}\) ) 
0.400 
0.415 
0.5 
0.400 
aprime (a’) 
1510.0 
1515.0 
1288.0 
1550.0 
fcorr (\(f_{corr}\) ) 
2.802 
2.812 
2.4 
2.802 
chb (\(c_{hb}\) ) 
8850.0 
8850.0 
7400.0 
8400.0 
sigmahbond (\(\sigma_{hb}\) ) 
0.00854 
0.00849 
0.0082 
0.00978 
aeff (\(a_{eff}\) ) 
6.94 
7.62 
7.1 
5.96 
lambda (\(\lambda\) ) 
0.130 
0.129 
0.14 
0.135 
omega (\(\omega\) ) 
0.212 
0.217 
0.21 
0.212 
eta (\(\eta\) ) 
9.65 
9.91 
9.15 
9.65 
chortf (\(c^\perp\) ) 
0.816 
0.816 
0.816 
0.816 
combi1998  combi2005 
combi2005 
combi1998 
combi1998 
combi2005 
hb_all  hb_hnof 
hb_hnof 
hb_hnof 
hb_hnof 
hb_hnof 
hb_temp  hb_notemp 
hb_temp 
hb_notemp 
hb_notemp 
hb_temp 
fast  nofast 
fast 
fast 
fast 
fast 
chortf
See Ref. 1 for the definitions: \(\sigma_v^\perp = \sigma_v^0  c^\perp \sigma_v\)
combi1998  combi2005
If the subkey combi1998 is included a thermodynamically inconsistent combinatorial contribution to the chemical potential \(\mu_i^{comb}\) of Ref. 1 is used. If the subkey combi2005 is included (default) a thermodynamically consistent combinatorial contribution of Ref. 3 is used. See the section on the combinatorial term and Ref. 3.
hb_all  hb_hnof
If the subkey hb_all is included hydrogen bond interaction can be included between segments that belong to H atoms and all other segments. If the subkey hb_hbnof is included (default) hydrogen bond interaction can be included only between segments that belong to H atoms that are bonded to N, O, or, F, and segments that belong to N, O, or F atoms.
hb_temp  hb_notemp
If the subkey hb_notemp is included the hydrogen bond interaction is not temperature dependent, as in Ref. 1. If the subkey hb_temp is included (default) the hydrogen bond interaction is temperature dependent, as in Ref. 3. See the section on the temperature dependent hydrogen bond interaction and Ref. 3.
fast  nofast
If the subkey fast is included the fast approximation is used. This fast approximation is the default. Use nofast for the original approach. See the section on the fast approximation for COSMORS calculations.
Links COSMORS GUI tutorial: set COSMORS parameters [1]
COSMORS element specific parameters¶
DISPERSION
{H dispH}
{C dispC}
{N dispN}
{...}
End
The following table gives the element specific dispersion constants. The ADF default values are optimized parameters for ADF calculations. The Klamt values can again be found in Ref. 1. The constants for F, Si, P, S, Br, and I in the ADF defaults were only fitted to a small number of experimental values or taken from Ref. 3.
element 
ADF Default 
ADF combi1998 
Klamt 

Ref. 1 

H 
0.0340 
0.0346 
0.041 
C 
0.0356 
0.0356 
0.037 
N 
0.0224 
0.0225 
0.027 
O 
0.0333 
0.0322 
0.042 
Cl 
0.0485 
0.0487 
0.052 
F 
0.026 

Si 
0.04 

P 
0.045 

S 
0.052 

Br 
0.055 

I 
0.062 
Note that not for all elements in the periodic system COSMORS parameters were fitted.
Links COSMORS GUI tutorial: set COSMORS parameters [1]
COSMOSAC general parameters¶
The ADF COSMORS program can calculate activity coefficients using the COSMOSAC 2013ADF model, based on Ref. 4. Like in the COSMORS method, pure compound vapor pressures can be given as input, for example, if experimental values are available. If these values are not specified then the pure compound vapor pressure will be calculated according to the COSMOSAC 2013ADF model. This part of the COSMOSAC 2013ADF has been implemented in ADF2016. The COSMOSAC 2013ADF parameters in Ref. 4 are optimized parameters for use with ADF COSMO result files. The authors of Ref. 6 reoptimized the revised COSMOSAC model 5 parameters for use with ADF COSMO result files, which is called here the COSMOSAC 2016ADF method. Note that the earlier COSMOSAC papers 7 5 do not include parameters that were optimized for use with ADF COSMO result files. The key COSMOSAC2013 needs to be included if one wants to do a COSMOSAC 2013ADF calculation. The key COSMOSACDHB needs to be included if one wants to do a COSMOSAC DHBADF calculation. For other COSMOSAC methods one needs to include the key COSMOSAC.
COSMOSAC2013  COSMOSAC  COSMOSACDHB
SACPARAMETERS
{AEFF aeff}
{FDECAY fdecay}
{SIGMA0 sigma0}
{RN rn}
{QN qn}
{AES aes}
{BES bes}
{COHOH cohoh}
{COTOT cotot}
{COHOT cohot}
{RAV rav}
{QS qs}
{rhbcut rhbcut}
{hb_temp  hb_notemp}
End
symbol 
2013ADF Xiong 
2016ADF Chen 
DHBADF Chen 
2010 Hsieh 
2007 Wang 

Ref. 4 
Ref. 6 
Ref. 8 
Ref. 5 
Ref. 7 

aeff (a_{eff} ) 
6.4813 
5.8447 
5.8447 
7.25 
7.25 
fdecay (f_{decay} ) 
3.57 
3.57 
3.57 
3.57 

sigma0 (\(\sigma\)_{0} ) 
0.01233 
0.007 
0.0063 
0.007 
0.007 
rn (r) 
66.69 
66.69 
66.69 
66.69 

qn (q) 
79.352 
79.53 
79.53 
79.53 
79.53 
aes (A_{ES} ) 
7877.13 
5920.84 
5920.84 
6525.69 
8451.77 
bes (B_{ES} ) 
0.0 
1.3950 10^{8} 
1.3950 10^{8} 
1.4859 10^{8} 
0.0 
cohoh (c_{OHOH} ) 
5786.72 
3551.10 
33306.83 
4013.78 
3484.42 
cotot (c_{OTOT} ) 
2739.58 
1077.26 
33306.83 
932.31 
3484.42 
cohot (c_{OHOT} ) 
4707.75 
3099.31 
33306.83 
3016.43 
3484.42 
rav (r_{av} ) 
0.51 

qs (q_{s} ) 
0.57 

rhbcut 
1.4432 

hb_temp  hb_notemp 
hb_notemp 
hb_notemp 
hb_notemp 
hb_notemp 
hb_notemp 
See also Refs. 4 5 for the meaning of the parameters a_{eff} , f_{decay} , \(\sigma\)_{0} , r, q, A_{ES} , B_{ES} , c_{OHOH} , c_{OTOT} , c_{OHOT} , r_{av} , q_{s} . The parameter names in 7 have been translated into parameter names used in Ref. 5, by calculating A_{ES} from 0.3 f_{pol} a_{eff} ^{3/2} /(2\(\epsilon_0\) ), using B_{ES} = 0, and using c_{OHOH} = c_{OTOT} = c_{OHOT} = c_{hb} . The parameters f_{decay} and r are not used in COSMOSAC 2013ADF 4. The parameters r_{av} and q_{s} are only used in COSMOSAC 2013ADF. The element specific COSMOSAC 2013ADF epsilon constants can be set with the block key EPSILON. These element specific epsilon constants can not be used in ADF’s implementation of earlier COSMOSAC methods. The parameter rhbcut is only used in COSMOSAC DHBADF 8. Note that the parameters for COSMOSAC DHBADF were reoptimized by Chen et al., and are different than in Ref. 8.
hb_temp  hb_notemp
If the subkey hb_notemp is included (default) the hydrogen bond interaction is not temperature dependent, as in Refs. 7 5 4. If the subkey hb_temp is included the temperature dependence of the hydrogen bond interaction f_{hb} (T) is the same as is described in the section on the temperature dependent hydrogen bond interaction.
Except for COSMOSAC 2013ADF, some COSMORS specific parameters are used in the next COSMOSAC methods:
COSMOSAC
SACPARAMETERS
...
{OMEGA omega}
{ETA eta}
End
symbol 
2013ADF Xiong 
2016ADF Chen, DHBADF Chen, 2010 Hsieh, 2007 Wang 

omega (\(\omega\)) 
0.212 

eta (\(\eta\)) 
9.00 
In ADF2016 these parameters are not used in the COSMOSAC 2013ADF method, only in the ADF implementation of the other COSMOSAC methods. The parameters \(\omega\), \(\eta\) and the element specific COSMORS dispersion constants are taken from the COSMORS model. The element specific COSMORS dispersion constants can be set with the block key DISPERSION. \(\omega\), \(\eta\), and the element specific COSMORS dispersion constants are used in a COSMORS like method for the calculation of pure compound vapor pressures.
COSMOSAC element specific parameters¶
COSMOSAC2013
EPSILON
{H epsH}
{C epsC}
{N epsN}
{...}
End
The following table gives the element specific epsilon constants in case of COSMOSAC 2013ADF, see Ref. 4. Like in the COSMORS method, pure compound vapor pressures can be given as input, for example, if experimental values are available. In these values ar not given, in ADF2016 the pure compound vapor pressure will be approximated using the the COSMOSAC 2013ADF method, which depend on these element specific epsilon constants. These constants will also have an effect on the calculated activity coefficients in case of a mixture. Note that these only have an effect in the ADF’s COSMOSAC 2013ADF implementation.
element 
2013ADF Xiong 

Ref. 4 

H 
338.13 
C.sp3 
29160.92 
C.sp2 
30951.83 
C.sp 
20685.98 
N.sp3 
23488.54 
N.sp2 
22663.34 
N.sp 
6390.40 
O.sp3H 
8527.06 
O.sp3 
8484.38 
O.sp2 
6736.85 
O.sp2N 
12145.28 
Cl 
8435.13 
F 
82512.21 
P 
56067.81 
S 
45065.19 
Br 
62947.83 
I 
105910.88 
Note that not for all elements in the periodic system COSMOSAC 2013ADF parameters were fitted.
If one leaves the EPSILON block keyword empty the contribution of the mixture dispersion to the activity coefficient will be zero.
EPSILON
End
Links COSMORS GUI tutorial: Expert option: set COSMOSAC 2013ADF parameters [1]
Technical and accuracy parameters¶
TECHNICAL
{RSCONV rsconv}
{SACCONV sacconv}
{MAXITER maxiter}
{BPCONV bpconv}
{BPMAXITER bpmaxiter}
{SOLCONV solconv}
{SOLMAXITER solmaxiter}
{SOLXILARGE solxilarge}
{EHDELTAT ehdeltaT}
End
symbol 
Default values 

rsconv 
10^{7} kcal/mol 
sacconv 
10^{7} 
maxiter 
10000 
bpconv 
10^{6} bar 
bpmaxiter 
40 
solconv 
10^{5} molar fraction 
solmaxiter 
40 
solxilarge 
0.99 molar fraction 
ehdeltaT 
1.0 Kelvin 
rsconv
Convergence criterion in kcal/mol in chemical potential calculation, not used in COSMOSAC 2013ADF. Default value 1e7 kcal/mol.
sacconv
Convergence criterion in activity coefficient calculation, only used in COSMOSAC 2013ADF. Default value 1e7.
maxiter
Maximum number of cycles in chemical potential or activity coefficients calculation. Default value 10000.
bpconv
Convergence criterion (bar) for isobar or solvent boiling point calculation. Default value 1e6 bar.
bpmaxiter
Maximum number of cycles in isobar or solvent boiling point calculation. Default value 40.
solconv
Convergence criterion (molar fraction) used in solubility calculations. Default value 1e5 molar fraction.
solmaxiter
Maximum number of cycles in solubility calculation. Default value 40.
solxilarge
Threshold for (im)miscibility (molar fraction) in solubility calculations. Above this value the mixture is considered to be fully miscible. Default value 0.99.
ehdeltaT
\(\Delta T\) (Kelvin) used in the calculation of the excess enthalpy using the GibbsHelmholtz equation and in the calculation of the enthalpy of vaporization using the ClausiusClapeyron equation using a numerical derivative with respect to T. Default value 1.0 Kelvin.
Links COSMORS GUI tutorial: set COSMORS or COSMOSAC 2013ADF parameters [1]
References
 1(1,2,3,4,5,6,7,8)
A. Klamt, V. Jonas, T. Bürger and J.C. Lohrenz, Refinement and Parametrization of COSMORS. J. Phys. Chem. A 102, 5074 (1998)
 2(1,2)
C.C. Pye, T. Ziegler, E. van Lenthe, J.N. Louwen, An implementation of the conductorlike screening model of solvation within the Amsterdam density functional package. Part II. COSMO for real solvents. Can. J. Chem. 87, 790 (2009)
 3(1,2,3,4,5)
A. Klamt, COSMORS From Quantum Chemistry to Fluid Phase Thermodynamics and Drug Design, Elsevier. Amsterdam (2005), ISBN 0444519947.
 4(1,2,3,4,5,6,7,8)
R. Xiong, S.I. Sandler, R.I. Burnett, An improvement to COSMOSAC for predicting thermodynamic properties, Ind. Eng. Chem. Res. 53, 8265 (2014)
 5(1,2,3,4,5,6)
C.M. Hsieh, S.I. Sandler, S.T. Lin, Improvements of COSMOSAC for vaporliquid and liquidliquid equilibrium predictions, Fluid Phase Equilib. 297, 90 (2010)
 6(1,2)
W.L. Chen, C.M. Hsieh, L. Yang, C.C. Hsu, S.T. Lin, A Critical Evaluation on the Performance of COSMOSAC Models for VaporLiquid and LiquidLiquid Equilibrium Predictions Based on Different Quantum Chemical Calculations, Ind. Eng. Chem. Res. 55, 9312 (2016)
 7(1,2,3,4)
S. Wang, S.I. Sandler, C.C. Chen, Refinement of COSMOSAC and the Applications, Ind. Eng. Chem. Res. 46, 7275 (2007)
 8(1,2,3)
W.L. Chen, S.T. Lin, Explicit consideration of spatial hydrogen bonding direction for activity coefficient prediction based on implicit solvation calculations, Phys.Chem.Chem.Phys. 19, 20367 (2017)