Anion Intercalation and Selectivity in NiFe LDH: Insights from Neural Network-Enhanced Molecular Dynamics [Published online J. Comput. Chem. Jpn., 24, 20-26, by J-STAGE]

[Published online Journal of Computer Chemistry, Japan Vol.24, 20-26, by J-STAGE]
<Title:> Anion Intercalation and Selectivity in NiFe LDH: Insights from Neural Network-Enhanced Molecular Dynamics
<Author(s):> Tien Quang NGUYEN, Susan Me ez ASPERA, Yingjie CHEN, Kaoru HISAMA, Michihisa KOYAMA
<Corresponding author E-Mill:> quang(at)shinshu-u.ac.jp
<Abstract:> Molecular dynamics (MD) simulations, accelerated by a universal neural network potential, were employed to investigate the dynamic behaviors of ten inorganic anions (Br, Cl, F, OH, NO3, H2PO2, H2PO3, HPO42-, CO32- and SO42-) intercalated into NiFe layered double hydroxide at varying hydration levels. Our results show that the lattice parameters along the layered double hydroxide (LDH) layers are minimally affected by the intercalated anions and water content, while the lattice parameter perpendicular to the layers, i.e., the basal spacing, is strongly influenced by the type of anion and hydration level. The basal spacing is closely correlated with the ionic radius and charge of the anions, as well as the amount of water uptake. Mean squared displacement (MSD) analysis reveals distinct behaviors of the anions under different hydration conditions. While some anions, such as NO3 and H2PO2, exhibit noticeable mobility, others remain largely immobilized, primarily due to strong electrostatic interactions with the LDH layers and water molecules. Hydration weakens the interaction between anions and the LDH but also restricts the mobility of anions due to the formation of hydration shells. These findings provide insights into anion dynamics and selectivity in NiFe LDH, which are critical for designing materials for anion removal applications.
<Keywords:> Layered-double hydroxides, Anion intercalation, Molecular dynamics, Neural network potential, Coulomb interactions
<URL:> https://www.jstage.jst.go.jp/article/jccj/24/1/24_2025-0001/_article/-char/ja/

アルキル鎖長が異なる有機半導体混合膜表面の分子動力学計算 [Published online J. Comput. Chem. Jpn., 24, 17-19, by J-STAGE]

[Published online Journal of Computer Chemistry, Japan Vol.24, 17-19, by J-STAGE]
<Title:> アルキル鎖長が異なる有機半導体混合膜表面の分子動力学計算
<Author(s):> 鈴木 陸央, 宮田 稜, 井上 悟, 長谷川 達生, 松井 弘之
<Corresponding author E-Mill:> t231542d(at)st.yamagata-u.ac.jp
<Abstract:> A mixed solution of organic semiconductors Ph-BTBT-Cn with different alkyl chain length (n) forms a high-quality molecular bilayer by suppressing layer-by-layer stacking when the molar fraction of the longer chains (χL) is 0.1 0.6. In this study, we performed molecular dynamics simulations to investigate the dynamics of alkyl chains in the mixed bilayer. The order parameters and dihedral angles of the alkyl chains were analyzed as a function of χL. The results revealed that increasing χL enhances the ordering of the longer alkyl chains, thereby reducing their torsional motion. A stochastic model of the number of free surplus chains explains the molar fraction dependence of film morphology.
<Keywords:> キーワード Molecular dynamics, Organic semiconductor, Surface alkyl chain, Ordering, Interlayer frustration
<URL:> https://www.jstage.jst.go.jp/article/jccj/24/1/24_2024-0038/_article/-char/ja/