Colloid-colloid interactions in charge-stabilized dispersions can to The crystallization process and polymorph selection of hard-core some extent be represented by the hard-core Yukawa model. Yukawa model are studied ...Colloid-colloid interactions in charge-stabilized dispersions can to The crystallization process and polymorph selection of hard-core some extent be represented by the hard-core Yukawa model. Yukawa model are studied by means of smart Monte Carlo simulations in the region of face-centered-cubic （fcc） phase. The contact value of bard-core Yukawa potential and the volume fraction of the colloids are fixed, while the Debye screening length can be varied. In the early stage of the crystallization, the precursors with relatively ordered liquid structure have been observed. Although the crystal structure of thermodynamically stable phase is fcc, the system crystallizes into a mixture of fcc and hexagonal close-packed （hcp） structures under small Debye screening length since the colloidal particles act as effective hard spheres. In the intermediate range of Debye screening length, the system crystallizes into a mixture of fcc, hcp, and body-centered-cubic （bcc）. The existence of metastable hcp and bcc structures can be interpreted as a manifestation of the Ostwald＇s step rule. Until the Debye screening length is large enough, the crystal structure obtained is almost a complete fcc suggesting the system eventually reaches to a thermodynamically stable state.展开更多
The two-Yukawa (TY) potential is a newly developed potential function for fluids. The Monte Carlo method was used to simulate the potential energy, intermolecular forces, radial distribution function, density profi...The two-Yukawa (TY) potential is a newly developed potential function for fluids. The Monte Carlo method was used to simulate the potential energy, intermolecular forces, radial distribution function, density profile, surface thickness and surface tension for a TY fluid at different temperatures. The results for a TY fluid are compared to those for a Lennard-Jone fluid, which shows that the surface properties are more sensitive to the intermolecular potential than the bulk properties and the repulsive action with a shore range can also influence the surface properties.展开更多
A density functional theory is applied to calculating the local density profiles of colloids confined in a slit-like pore as well as the radial distribution functions of bulk colloids. The interaction between the coll...A density functional theory is applied to calculating the local density profiles of colloids confined in a slit-like pore as well as the radial distribution functions of bulk colloids. The interaction between the colloidal particles is described using a hard-core Yukawa model. The excess Helmholtz energy functional is a combination of the modified fundamental measure theory of Yu and Wu （2002） for the hard-core contribution and a corrected mean-field theory for the attractive contribution. Comparison with the results from the Monte Carlo simulations shows that the corrected theory improves the density profiles of colloids in the vicinity of contact over the original mean-field theory. Both the present corrected theory and simulations suggest that there are depletion and desorption for the colloid with strong attraction between particles at low temperature.展开更多
基金the National Natural Science Foundation of China (11172302, 11302226, 10972217)the Opening Fund of State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, China (LNM201503)
文摘Colloid-colloid interactions in charge-stabilized dispersions can to The crystallization process and polymorph selection of hard-core some extent be represented by the hard-core Yukawa model. Yukawa model are studied by means of smart Monte Carlo simulations in the region of face-centered-cubic （fcc） phase. The contact value of bard-core Yukawa potential and the volume fraction of the colloids are fixed, while the Debye screening length can be varied. In the early stage of the crystallization, the precursors with relatively ordered liquid structure have been observed. Although the crystal structure of thermodynamically stable phase is fcc, the system crystallizes into a mixture of fcc and hexagonal close-packed （hcp） structures under small Debye screening length since the colloidal particles act as effective hard spheres. In the intermediate range of Debye screening length, the system crystallizes into a mixture of fcc, hcp, and body-centered-cubic （bcc）. The existence of metastable hcp and bcc structures can be interpreted as a manifestation of the Ostwald＇s step rule. Until the Debye screening length is large enough, the crystal structure obtained is almost a complete fcc suggesting the system eventually reaches to a thermodynamically stable state.
基金Supported by the National Natural Science Foundationof China (Nos. 2 973 6170 and 2 0 10 60 0 7) ,theFundam ental Research Fund of Tsinghua U niversity(No. JC19990 3 8) and the Scientific ResearchFoundation for Returned Overseas Chinese Scholars
文摘The two-Yukawa (TY) potential is a newly developed potential function for fluids. The Monte Carlo method was used to simulate the potential energy, intermolecular forces, radial distribution function, density profile, surface thickness and surface tension for a TY fluid at different temperatures. The results for a TY fluid are compared to those for a Lennard-Jone fluid, which shows that the surface properties are more sensitive to the intermolecular potential than the bulk properties and the repulsive action with a shore range can also influence the surface properties.
基金This work is sponsored by the National Natural Science Foun’ dation of China(Grant No．20376037) the National Basic Research Pr0gram of China(Grant No．2003CB61 5700)
文摘A density functional theory is applied to calculating the local density profiles of colloids confined in a slit-like pore as well as the radial distribution functions of bulk colloids. The interaction between the colloidal particles is described using a hard-core Yukawa model. The excess Helmholtz energy functional is a combination of the modified fundamental measure theory of Yu and Wu （2002） for the hard-core contribution and a corrected mean-field theory for the attractive contribution. Comparison with the results from the Monte Carlo simulations shows that the corrected theory improves the density profiles of colloids in the vicinity of contact over the original mean-field theory. Both the present corrected theory and simulations suggest that there are depletion and desorption for the colloid with strong attraction between particles at low temperature.
