Convergence test is a way of optimizing a simulation to use limited computational resources efficiently. It is important to find a proper initial input setting for simulation research to decide the accuracy and reliability of the simulation. Read more
Convergence test is a way of optimizing a simulation to use limited computational resources efficiently. It is important to find a proper initial input setting for simulation research to decide the accuracy and reliability of the simulation. Read more
The energy for bonding can be calculated using the difference between a bonded structure and a dissociated one. This energy, which is necessary to separate an atom from the solid, is called cohesive energy. Read more
Cohesive energy defined as the difference between the energy per atom in a solid and the energy of a single atom. It can be used to understand the property of crystal such as in finding the correlation effect of an ionic crystal or identifying the stability of the surface. Read more
Under the adsorption process, the energy change is called adsorption energy. This energy is mainly used when calculating the chemical engineering properties, exploring the adsorption mechanism, or determining the energetic heterogeneity of the surface of a solid. Read more
When modeling a slab structure, after the relaxation of the unit cell, use the optimized unit cell to create a slab structure. Then, it can reduce the time for calculating a slab structure. In addition, with the use of the two energies, you can get the surface energy. Read more
If some of the crystal is moved, a stacking fault is created. The energy generated by the stacking fault is called stacking fault energy (SFE). The stacking fault energy can be used to determine the thermodynamic stability of a crystal structure or to find out the deformation behavior. Read more
For a material is isotropically compressed, at a small volume change, pressure is proportional to the volume strain, and the proportional constant is called the bulk modulus. The bulk modulus could be calculated by applying the data obtained from the several scf calculations. Read more
Different pseudopotentials yield different energy values. Therefore, energy values should not be compared directly. But the trend is consistent. So compare the difference in the values. Read more
Formation Energy is the value to be used as a measure of the amount of energy entering and exiting a chemical reaction, thus providing a basis for determining thermodynamic stability. Read more
Van der Waals Correction is performed to improve the precision of GGA. Van der Waals Correction, such as DFT+D3, corrects the correlation term of exchange-correlation potential by adding dispersion term. Read more
The density of states (DOS) is the number of different electron states whose occupation is allowed at a specific energy level. DOS is a very important data to describe the electronic structure properties of a macroscopic system quantum-mechanically. Read more
This Example looks at the importance of setting calculation parameters including the number of k-points in DOS calculations. The DOS graph is highly affected by the density of k-points. The DOS graph samples more k-points if denser k-points are set, resulting in a broad graph. Read more
GGA has a fundamental characteristic of underestimating bandgap, Hartree-Fock has an overestimate bandgap. This is due to the exchange potential approximation, so we can correct bandgap and other electronic structures by mixing both functionals. Read more
With a DFT calculation, you can calculate an electron charge density. With Materials Square, you can conveniently find and visualize the charge density data by carrying out a plane-wave basis DFT calculation of Quantum Espresso. Read more
The artificial electric field added automatically to delete a 'potential jump' in the boundary to asymmetry slab structure. So we should do dipole correction by adding a 'sawtooth potential' to the vacuum region to delete the artificial electric field. Read more
An insulator has a sufficient bandgap and the Fermi level is observed within the bandgap. However, of the case of a conductor, the conduction and valence bands are overlapped without any gaps near the Fermi level. Read more
When you observe the band structure of silicon, the band gaps and the Fermi level existing between them can be seen. However, the band gap moves below or above the Fermi level, thus causing it to be electric property change. Read more
To accurately draw a band structure, you need to set a k-point sampling path by passing the high symmetry point of the Brillouin zone, which depends on the crystal system. Read more
Using the Electric field correction option, we can adjust the bandgap of Graphene bilayer by applying the electric field to the Graphene bilayer. Read more
According to the relativistic theory, the dipole moments of electrons weakly interact with the orbital motions they make. This interaction is called Spin-orbit coupling (SOC). Applying SOC corrections to the simulation yielding the fine-structure of the system. Read more
DFT+U is effective correction method for the correlation energy error in DFT simulation. Read more