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Iowa State University

Density functional theory

Biological and Chemical Physics

Articles 1 - 6 of 6

Full-Text Articles in Physics

Theoretical Prediction Of Crystallization Kinetics Of A Supercooled Lennard-Jones Fluid, K. G. S. H. Gunawardana, Xueyu Song May 2018

Theoretical Prediction Of Crystallization Kinetics Of A Supercooled Lennard-Jones Fluid, K. G. S. H. Gunawardana, Xueyu Song

Chemistry Publications

The first order curvature correction to the crystal-liquid interfacial free energy is calculated using a theoretical model based on the interfacial excess thermodynamic properties. The correction parameter (δ), which is analogous to the Tolman length at a liquid-vapor interface, is found to be 0.48 ± 0.05 for a Lennard-Jones (LJ) fluid. We show that this curvature correction is crucial in predicting the nucleation barrier when the size of the crystal nucleus is small. The thermodynamic driving force (Δμ) corresponding to available simulated nucleation conditions is also calculated by combining the simulated data with a classical density functional theory ...


Adsorption Of Dysprosium On The Graphite (0001) Surface: Nucleation And Growth At 300 K, Emma J. Kwolek, Huaping Lei, Ann Lii-Rosales, Mark Wallingford, Yinghui Zhou, Cai-Zhuang Wang, Michael C. Tringides, James W. Evans Dec 2016

Adsorption Of Dysprosium On The Graphite (0001) Surface: Nucleation And Growth At 300 K, Emma J. Kwolek, Huaping Lei, Ann Lii-Rosales, Mark Wallingford, Yinghui Zhou, Cai-Zhuang Wang, Michael C. Tringides, James W. Evans

Physics and Astronomy Publications

We have studied nucleation and growth of Dy islands on the basal plane of graphite at 300 K using scanning tunneling microscopy, density functional theory (DFT) in a form that includes van der Waals interactions, and analytic theory. The interaction of atomic Dy with graphite is strong, while the diffusion barrier is small. Experiment shows that at 300 K, the density of nucleated islands is close to the value predicted for homogeneous nucleation, using critical nucleus size of 1 and the DFT-derived diffusion barrier. Homogeneous nucleation is also supported by the monomodal shape of the island size distributions. Comparison with ...


Comparison Of S-Adsorption On (111) And (100) Facets Of Cu Nanoclusters, Jeffrey S. Boschen, Jiyoung Lee, Theresa L. Windus, James W. Evans, Patricia A. Thiel, Da-Jiang Liu Oct 2016

Comparison Of S-Adsorption On (111) And (100) Facets Of Cu Nanoclusters, Jeffrey S. Boschen, Jiyoung Lee, Theresa L. Windus, James W. Evans, Patricia A. Thiel, Da-Jiang Liu

Physics and Astronomy Publications

In order to gain insight into the nature of chemical bonding of sulfur atoms on coinage metal surfaces, we compare the adsorption energy and structural parameters for sulfur at four-fold hollow (4fh) sites on (100) facets and at three-fold hollow (3fh) sites on (111) facets of Cu nanoclusters. Consistent results are obtained from localized atomic orbital and plane-wave based density functional theory using the same functionals. PBE and its hybrid counterpart (PBE0 or HSE06) also give similar results. 4fh sites are preferred over 3fh sites with stronger bonding by ∼0.6 eV for nanocluster sizes above ∼280 atoms. However, for ...


Adsorption And Diffusion Of Ru Adatoms On Ru(0001)-Supported Graphene: Large-Scale First-Principles Calculations, Yong Han, James W. Evans Oct 2015

Adsorption And Diffusion Of Ru Adatoms On Ru(0001)-Supported Graphene: Large-Scale First-Principles Calculations, Yong Han, James W. Evans

Physics and Astronomy Publications

Large-scale first-principles density functional theory calculations are performed to investigate the adsorption and diffusion of Ru adatoms on monolayer graphene (G) supported on Ru(0001). The G sheet exhibits a periodic moiré-cell superstructure due to lattice mismatch. Within a moirécell, there are three distinct regions: fcc, hcp, and mound, in which the C6-ring center is above a fcc site, a hcp site, and a surface Ru atom of Ru(0001), respectively. The adsorption energy of a Ru adatom is evaluated at specific sites in these distinct regions. We find the strongest binding at an adsorption site above a C atom ...


Low-Temperature Adsorption Of H2s On Ag(111), Selena M. Russell, Da-Jiang Liu, Maki Kawai, Yousoo Kim, Patricia A. Thiel Jan 2010

Low-Temperature Adsorption Of H2s On Ag(111), Selena M. Russell, Da-Jiang Liu, Maki Kawai, Yousoo Kim, Patricia A. Thiel

Chemistry Publications

H2S forms a rich variety of structures on Ag(111) at low temperature and submonolayer coverage. The molecules decorate step edges, exist as isolated entities on terraces, and aggregate into clusters and islands, under various conditions. One type of island exhibits a (×)R25.3° unit cell. Typically, molecules in the clusters and islands are separated by about 0.4 nm, the same as the S–S separation in crystalline H2S. Density functional theory indicates that hydrogen-bonded clusters contain two types of molecules. One is very similar to an isolated adsorbed H2S molecule, with both ...


Unbiased Density Functional Solutions Of Freezing In Binary Mixtures Of Hard Or Soft Spheres, M. Valera, R. F. Bielby, F. J. Pinksi, Duane D. Johnson Jan 2001

Unbiased Density Functional Solutions Of Freezing In Binary Mixtures Of Hard Or Soft Spheres, M. Valera, R. F. Bielby, F. J. Pinksi, Duane D. Johnson

Duane D. Johnson

various size ratios, σ2/σ1, using density functional theory. The Grand Potential is minimized using an unbiased, discrete, real-space mesh that does not constrain the shape of the density, and, in many cases, leads to solutions qualitatively different from those using Gaussians and plane-waves. Besides the usual face-centered-cubic solid-solution phase for σ2/σ1≈1.0, we find a sublattice-melt phase for σ2/σ1=0.85–0.5 (where the small-sphere density is nonlocalized and multi-peaked) and the NaCl phase for σ2/σ1=0.45–0.35 (when the small-sphere density again sharpens). For a range of size ratios of soft ...