Assessing the accuracy of quantum Monte Carlo and density functional theory for energetics of small water clusters

Details Assessing the accuracy of quantum Monte Carlo and density functional theory for energetics of small water clusters Assessing the accuracy of quantum Monte Carlo and density functional theory for energetics of small water clusters

2012-04-17

arxiv.org/abs/1204.3757v1

Physics

Condensed Matter

Materials Science

34 pages, 6 figures

Scientific paper

We present a detailed study of the energetics of water clusters (H$_2$O)$_n$ with $n \le 6$, comparing diffusion Monte Carlo (DMC) and approximate density functional theory (DFT) with well converged coupled-cluster benchmarks. We use the many-body decomposition of the total energy to classify the errors of DMC and DFT into 1-body, 2-body and beyond-2-body components. Using both equilibrium cluster configurations and thermal ensembles of configurations, we find DMC to be uniformly much more accurate than DFT, partly because some of the approximate functionals give poor 1-body distortion energies. Even when these are corrected, DFT remains considerably less accurate than DMC. When both 1- and 2-body errors of DFT are corrected, some functionals compete in accuracy with DMC; however, other functionals remain worse, showing that they suffer from significant beyond-2-body errors. Combining the evidence presented here with the recently demonstrated high accuracy of DMC for ice structures, we suggest how DMC can now be used to provide benchmarks for larger clusters and for bulk liquid water.

Affiliated with

Also associated with

No associations

Rating

Assessing the accuracy of quantum Monte Carlo and density functional theory for energetics of small water clusters does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Assessing the accuracy of quantum Monte Carlo and density functional theory for energetics of small water clusters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Assessing the accuracy of quantum Monte Carlo and density functional theory for energetics of small water clusters will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-289736