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This study integrates Density Functional Theory (DFT) calculations via the SIESTA code with Event-Driven Molecular Dynamics (EDMD) simulations to investigate the structural, electronic, and dynamical properties of H \(_2\) O, MgO, CH \(_4\) , and CdS, emphasizing their synergies in multicomponent energy systems, including CdS/MgO heterojunction photocatalysts for hydrogen evolution and MgO-promoted CH \(_4\) /H \(_2\) O reforming for syngas production and energy storage. Structures were constructed using Avogadro and Jmol, with norm-conserving pseudopotentials generated via ATOM; convergence was achieved at a 200 Ry mesh cutoff and 0.04 Å \(^{-1}\) k-point spacing, validated across GGA (PBE) and LDA approximations to capture exchange-correlation effects accurately. DFT elucidates electronic structures, revealing molecular band gaps > 10 eV for H \(_2\) O and CH \(_4\) , a wide 4.5 eV gap in MgO (O 2p valence, Mg 3s conduction), and a narrow 1.8 eV gap in CdS (S 3p valence, Cd 5s conduction), yielding a type-II band alignment with \(\sim \)  2.7 eV conduction band offset that promotes efficient charge separation at CdS/MgO interfaces for enhanced photocatalytic performance. Complementary EDMD, modeling hard-sphere interactions in a 300 K periodic box, quantifies mass-dependent diffusion: rapid for CH \(_4\) ( \(\sim \)  450 Å \(^2\) MSD in 5 ps) and H \(_2\) O ( \(\sim \)  400 Å \(^2\) ), versus sluggish for MgO ( \(\sim \)  50 Å \(^2\) ) and CdS (< 10 Å \(^2\) ), with velocity distributions confirming Maxwell–Boltzmann equilibrium. This DFT-EDMD synergy bridges quantum electronic insights with molecular transport dynamics, demonstrating MgO’s role in stabilizing CH \(_4\) /H \(_2\) O mixtures and offering a validated multi-scale framework for rational design of advanced clean energy materials. These prototypical components were selected to model reactants (H \(_2\) O, CH \(_4\) ) and catalysts (MgO, CdS) in hybrid energy processes, such as MgO-stabilized steam reforming of CH \(_4\) /H \(_2\) O for syngas production and CdS/MgO heterojunctions for photocatalytic H \(_2\) evolution, where emergent multicomponent synergies enhance efficiency beyond isolated studies.

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DFT and EDMD Study of H \(_{2}\) O, MgO, CH \(_{4}\) , and CdS: Multicomponent Insights for Energy Materials

  • 会议论文

  • 发表日期：

    2026年

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  • Manjeet Seth,
  • Seema Seth,
  • Sanjana Seth,
  • Mandeep Seth,
  • Roshani Seth,
  • Sushil Seth

摘要

This study integrates Density Functional Theory (DFT) calculations via the SIESTA code with Event-Driven Molecular Dynamics (EDMD) simulations to investigate the structural, electronic, and dynamical properties of H \(_2\) O, MgO, CH \(_4\) , and CdS, emphasizing their synergies in multicomponent energy systems, including CdS/MgO heterojunction photocatalysts for hydrogen evolution and MgO-promoted CH \(_4\) /H \(_2\) O reforming for syngas production and energy storage. Structures were constructed using Avogadro and Jmol, with norm-conserving pseudopotentials generated via ATOM; convergence was achieved at a 200 Ry mesh cutoff and 0.04 Å \(^{-1}\) k-point spacing, validated across GGA (PBE) and LDA approximations to capture exchange-correlation effects accurately. DFT elucidates electronic structures, revealing molecular band gaps > 10 eV for H \(_2\) O and CH \(_4\) , a wide 4.5 eV gap in MgO (O 2p valence, Mg 3s conduction), and a narrow 1.8 eV gap in CdS (S 3p valence, Cd 5s conduction), yielding a type-II band alignment with \(\sim \)  2.7 eV conduction band offset that promotes efficient charge separation at CdS/MgO interfaces for enhanced photocatalytic performance. Complementary EDMD, modeling hard-sphere interactions in a 300 K periodic box, quantifies mass-dependent diffusion: rapid for CH \(_4\) ( \(\sim \)  450 Å \(^2\) MSD in 5 ps) and H \(_2\) O ( \(\sim \)  400 Å \(^2\) ), versus sluggish for MgO ( \(\sim \)  50 Å \(^2\) ) and CdS (< 10 Å \(^2\) ), with velocity distributions confirming Maxwell–Boltzmann equilibrium. This DFT-EDMD synergy bridges quantum electronic insights with molecular transport dynamics, demonstrating MgO’s role in stabilizing CH \(_4\) /H \(_2\) O mixtures and offering a validated multi-scale framework for rational design of advanced clean energy materials. These prototypical components were selected to model reactants (H \(_2\) O, CH \(_4\) ) and catalysts (MgO, CdS) in hybrid energy processes, such as MgO-stabilized steam reforming of CH \(_4\) /H \(_2\) O for syngas production and CdS/MgO heterojunctions for photocatalytic H \(_2\) evolution, where emergent multicomponent synergies enhance efficiency beyond isolated studies.