TY - JOUR
T1 - Integral equation study of hydrophobic interaction
T2 - A comparison between the simple point charge model for water and a Lennard-Jones model for solvent
AU - Sumi, Tomonari
AU - Sekino, Hideo
N1 - Funding Information:
This work was partly supported by Grant-in-Aid for Science Research from the Ministry of Education, Culture, Sports, Science and Technology (No. 17300094) and CREST-JST.
PY - 2007
Y1 - 2007
N2 - The hydrophobic interaction that is characterized by a potential of mean force (PMF) between spherical apolar solutes immersed in the simple point charge (SPCE) model for water was studied using an interaction site model integral equation based on a density-functional theory for molecular fluids. For comparison with the PMFs for various size solutes in the SPCE model, the PMFs in a Lennard-Jones (LJ) model for a solvent whose diameter is same as the SPCE model were also studied using a hypernetted chain integral equation. It is noted in the LJ model that the hydrogen bond and its network structure are completely ignored, but the translational entropy is taken into account. Both PMFs obtained from the SPCE model and from the LJ model have a large first minimum at a contact distance of solutes. In the case that the solute size is about three times larger than water, these PMFs also have a large maximum at a longer distance than the contact position. The strong attraction is attributed to the translational entropy of the solvent, and that the large activation barrier is arising from the weak attraction between the solute and the solvent. The comparison between the SPCE model and the LJ solvent model suggests that the qualitative description of the hydrophobic interaction is possible by using the LJ solvent model. On the other hand, the dewetting tendency on the surface of the apolar solute in a room condition is observed only on the SPCE model. These results indicate that the characteristics of water such as the hydrogen bond affect rather the hydrophobic hydration than the hydrophobic interaction.
AB - The hydrophobic interaction that is characterized by a potential of mean force (PMF) between spherical apolar solutes immersed in the simple point charge (SPCE) model for water was studied using an interaction site model integral equation based on a density-functional theory for molecular fluids. For comparison with the PMFs for various size solutes in the SPCE model, the PMFs in a Lennard-Jones (LJ) model for a solvent whose diameter is same as the SPCE model were also studied using a hypernetted chain integral equation. It is noted in the LJ model that the hydrogen bond and its network structure are completely ignored, but the translational entropy is taken into account. Both PMFs obtained from the SPCE model and from the LJ model have a large first minimum at a contact distance of solutes. In the case that the solute size is about three times larger than water, these PMFs also have a large maximum at a longer distance than the contact position. The strong attraction is attributed to the translational entropy of the solvent, and that the large activation barrier is arising from the weak attraction between the solute and the solvent. The comparison between the SPCE model and the LJ solvent model suggests that the qualitative description of the hydrophobic interaction is possible by using the LJ solvent model. On the other hand, the dewetting tendency on the surface of the apolar solute in a room condition is observed only on the SPCE model. These results indicate that the characteristics of water such as the hydrogen bond affect rather the hydrophobic hydration than the hydrophobic interaction.
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U2 - 10.1063/1.2718520
DO - 10.1063/1.2718520
M3 - Article
C2 - 17444724
AN - SCOPUS:34247262684
SN - 0021-9606
VL - 126
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
IS - 14
M1 - 144508
ER -