Problem 2: Calculate the tetrahedral and octahedral self-interstitial atom (SIA) formation energy in a-Fe, and calculate

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Problem 2 Calculate The Tetrahedral And Octahedral Self Interstitial Atom Sia Formation Energy In A Fe And Calculate 1 (127.9 KiB) Viewed 45 times

Problem 2: Calculate the tetrahedral and octahedral self-interstitial atom (SIA) formation energy in a-Fe, and calculate the <100>, <110>, and <111> dumbbell-shaped SIA formation energy. Please see Fig.1 for the schematic diagram of the SIA structure. (40 pts) Firstly, you need to create a bcc Fe supercell, find a suitable supercell size for the calculations. Identify the number of atoms N in the cell and compute the initial potential energy Epot(N). Then introduce an additional Fe atom into the supercell to create a self-interstitial atom defect. Relax the supercell via energy minimization (conjugate gradient, etc.), and calculate the final potential energy Epot(N+1). The SIA formation energy can be calculated by the following equation. N +1 Esta = Epo: (N+1) – E por (N) N SIA where Epot(N+1) and Epot(N) are the potential energy of the system with and without a self-interstitial atom, respectively. Two types of SIA defects (see Fig 1 below [1]): 1) interstitial, where an extra atom is inserted at a specified location that does not correspond to an existing atom. 2) dumbbell interstitial, where an atom at a specified location is replaced by a pair of atoms equidistant from the original atom's position.