DFT SIMULATION

Ground State Energy Calculation

We compute the ground state energy of materials using first-principles DFT calculations in VASP to determine their most stable configuration. By performing self-consistent field (SCF) calculations, we minimize the total energy with respect to electron density until convergence is achieved. The choice of exchange-correlation functional (e.g., GGA-PBE, PBEsol, DFT+U) influences the accuracy of the calculated energy.

Energy vs Volume

In MSRL, we perform Energy vs. Volume (E-V) calculations using VASP to determine the equilibrium lattice parameters and bulk modulus of materials. This involves computing the total energy of a material’s unit cell for different volumes and fitting the results to the Birch-Murnaghan equation, to extract key properties like equilibrium volume and compressibility. These simulations help to understand structural stability and provide essential input for further electronic, optical, phonon, etc property calculations, complementing our experimental findings in material synthesis and characterization.

Crystallographic Parameters

By performing static calculations with various exchange-correlation functionals such as GGA-PBE, GGA-PBEsol, GGA-PBE + VdW, and DFT+U, we extract the crystallographic parameters directly from VASP output files. This analysis allows us to compare how different functionals influence the lattice constants and structural properties of materials, providing critical insights into their physical dimensions.

Density of States

We compute the Density of States (DOS) using VASP with various exchange-correlation functionals to determine the band gap of materials accurately. By comparing the calculated band gaps with experimental values, we assess the performance of different functionals and select the most suitable one for reliable electronic structure predictions. This approach helps us understand the influence of functionals on the electronic states, band edge positions, and orbital contributions, ensuring accurate modeling for material applications.

Band Structure

Band Structure calculations in VASP with different exchange-correlation functionals is employed to accurately match the band gap with experimental one. The band structure not only helps validate the band gap but also reveals whether the material has a direct or indirect band gap. Additionally, we extract the effective mass from band structure data, providing key insights into carrier mobility and transport properties

Phonon & Born Charge Calculation

We perform phonon calculations using VASP and Phonopy to analyze the vibrational properties of materials under different exchange-correlation functionals. These calculations help determine phonon dispersion, vibrational stability, and thermal properties by identifying soft modes or imaginary frequencies. Additionally, we compute Born effective charges (BEC) to understand lattice dynamics and electron-phonon interactions, which are crucial for predicting polarization effects and dielectric properties. By comparing results across functionals, we ensure accurate theoretical predictions that complement our experimental studies on material stability and optical behavior.

Raman Peak Position Calculation

Using Quantum ESPRESSO, we calculate Raman peak positions and vibrational modes for different exchange-correlation functionals to analyze their impact on lattice dynamics. These theoretical Raman spectra are then compared with experimental data to assess the accuracy of each functional in predicting vibrational properties.

Elastic Calculation

Using DFT calculations in VASP, we determine the elastic properties of materials under different functionals. The computed elastic constants (Cij) provide insights into mechanical stability, while the bulk, shear, and Young’s moduli reveal material stiffness and ductility. Additionally, we analyze elastic anisotropy to understand directional mechanical behavior. Comparing these results with experimental data ensures accurate predictions of mechanical performance.

Optical Properties Calculation

We analyze the optical properties of materials using DFT-based first-principles calculations in VASP. The complex dielectric function ε(ω) = ε₁(ω) + iε₂(ω) is computed to investigate absorption, reflectivity, refractive index, and energy loss spectra across different functionals. Band gap estimations from Tauc plots and electronic transitions help determine the material's suitability for photocatalysis and optoelectronic applications. By comparing computational results with experimental data, we ensure accurate modeling of optical behavior for advanced material design.

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