Molecule tests

Warning: this page is outdated. For performance of GPAW for molecular systems refer to G2-1 database.

Atomization energies and bond lengths for a set of small molecules have been calculated with the PBE functional. All calculations are done with a grid spacing of 0.16 Å, zero-boundary conditions and approximately 6 Å of vacuum surrounding the molecules. Compensation charges are expanded with correct multipole moments up to \(\ell_{max}=2\). Open-shell atoms are treated as non-spherical with integer occupation numbers, and zero-point energy is not included in the atomization energies. The numbers are compared to very accurate, state-of-the-art, PBE calculations [1]. The script that does the calculations is molecule_test.py.

Bond lengths

../_images/bondlengths.png

Bondlengths in Å:

dimer GPAW reference error
\(\rm{BeH}\ (\rm{beryllium}\ \rm{monohydride})\) 1.357 1.354 +0.003
\(\rm{ClO}\) 1.584 1.576 +0.008
\(\rm{CO}\) 1.141 1.136 +0.005
\(\rm{CN}\ (\rm{Cyano}\ \rm{radical})\) 1.172 1.173 -0.001
\(\rm{FCl}\) 1.652 1.648 +0.004
\(\rm{LiH}\) 1.611 1.604 +0.007
\(\rm{F}_2\) 1.414 1.414 +0.000
\(\rm{LiF}\) 1.607 1.583 +0.024
\(\rm{Na}_2\) 3.077 3.087 -0.010
\(\rm{CH}(\rm{Methylidyne})\) 1.135 1.136 -0.001
\(\rm{HCl}\) 1.289 1.287 +0.002
\(\rm{Li}_2\) 2.728 2.728 +0.000
\(\rm{N}_2\) 1.101 1.103 -0.002
\(\rm{O}_2\) 1.234 1.218 +0.016
\(\rm{Cl}_2\) 2.007 1.999 +0.008

Atomization energies

Atomization energies in eV:

molecule GPAW reference error
\(\rm{BeH}\ (\rm{beryllium}\ \rm{monohydride})\) 2.399 2.407 -0.008
\(\rm{C}_2\rm{H}_2\) 18.046 17.974 +0.072
\(\rm{C}_2\rm{H}_4\) 24.837 24.761 +0.076
\(\rm{C}_2\rm{H}_6\) 31.129 31.049 +0.080
\(\rm{CH}(\rm{Methylidyne})\) 3.675 3.673 +0.002
\(\rm{CH}_2\ (^1\rm{A}_1)\) 7.767 7.754 +0.013
\(\rm{CH}_2\ (^3\rm{B}_1)\) 8.441 8.430 +0.011
\(\rm{CH}_3\) 13.458 13.430 +0.028
\(\rm{CH}_3\rm{Cl}\) 17.356 17.320 +0.036
\(\rm{H}_3\rm{COH}\) 22.552 22.519 +0.033
\(\rm{H}_3\rm{CSH}\) 20.745 20.719 +0.026
\(\rm{CH}_4\) 18.233 18.196 +0.037
\(\rm{CN}\ (\rm{Cyano}\ \rm{radical})\) 8.535 8.564 -0.029
\(\rm{CO}\) 11.617 11.648 -0.031
\(\rm{CO}_2\) 18.002 18.013 -0.011
\(\rm{SC}\) 7.790 7.784 +0.006
\(\rm{Cl}_2\) 2.841 2.853 -0.012
\(\rm{FCl}\) 3.134 3.135 -0.001
\(\rm{ClO}\) 3.515 3.539 -0.024
\(\rm{F}_2\) 2.312 2.281 +0.031
\(\rm{H}_2\rm{CO}\) 16.734 16.717 +0.017
\(\rm{H}_2\rm{O}\) 10.119 10.134 -0.015
\(\rm{HOOH}\) 12.204 12.211 -0.007
\(\rm{HCN}\) 14.190 14.150 +0.040
\(\rm{HCO}\) 12.790 12.788 +0.002
\(\rm{HCl}\) 4.606 4.610 -0.004
\(\rm{HF}\) 6.156 6.136 +0.020
\(\rm{HOCl}\ (\rm{hypochlorous}\ \rm{acid})\) 7.590 7.597 -0.007
\(\rm{Li}_2\) 0.865 0.863 +0.002
\(\rm{LiF}\) 5.981 6.002 -0.021
\(\rm{LiH}\) 2.331 2.320 +0.011
\(\rm{N}_2\) 10.572 10.568 +0.004
\(\rm{H}_2\rm{NNH}_2\) 19.713 19.631 +0.082
\(\rm{NH}\) 3.836 3.842 -0.006
\(\rm{NH}_2\) 8.186 8.183 +0.003
\(\rm{NH}_3\) 13.124 13.083 +0.041
\(\rm{NO}\) 7.417 7.459 -0.042
\(\rm{Na}_2\) 0.766 0.768 -0.002
\(\rm{NaCl}\) 4.101 4.059 +0.042
\(\rm{O}_2\) 6.158 6.214 -0.056
\(\rm{OH}\) 4.749 4.757 -0.008
\(\rm{P}_2\) 5.232 5.269 -0.037
\(\rm{PH}_2\ (\rm{Phosphino}\ \rm{radical})\) 6.674 6.700 -0.026
\(\rm{PH}_3\) 10.329 10.364 -0.035
\(\rm{S}_2\) 4.980 5.004 -0.024
\(\rm{SH}_2\) 7.875 7.892 -0.017
\(\rm{SO}\) 6.085 6.136 -0.051
\(\rm{SO}_2\) 12.057 12.190 -0.133
\(\rm{Si}_2\ (\rm{Silicon}\ \rm{diatomic})\) 3.507 3.526 -0.019
\(\rm{Si}_2\rm{H}_6\) 22.458 22.528 -0.070
\(\rm{SiH}_2\ (^1\rm{A}_1)(\rm{silicon}\ \rm{dihydride})\) 6.388 6.414 -0.026
\(\rm{SiH}_2\ (^3\rm{B}_1)(\rm{silicon}\ \rm{dihydride})\) 5.670 5.694 -0.024
\(\rm{SiH}_3\) 9.601 9.636 -0.035
\(\rm{SiH}_4\) 13.542 13.586 -0.044
\(\rm{SiO}\) 8.428 8.482 -0.054

References

[1]“The Perdew-Burke-Ernzerhof exchange-correlation functional applied to the G2-1 test set using a plane-wave basis set”, J. Paier, R. Hirschl, M. Marsman and G. Kresse, J. Chem. Phys. 122, 234102 (2005)
[2] “Molecular and Solid State Tests of Density Functional
Approximations: LSD, GGAs, and Meta-GGAs”, S. Kurth, J. P. Perdew and P. Blaha, Int. J. Quant. Chem. 75, 889-909 (1999)
[3]“Comment on ‘Generalized Gradient Approximation Made Simple’”, Y. Zhang and W. Yang, Phys. Rev. Lett.
[4] Reply to [3], J. P. Perdew, K. Burke and M. Ernzerhof