exercises:2019_conexs_newcastle:ex3
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exercises:2019_conexs_newcastle:ex3 [2019/09/09 08:11] – abussy | exercises:2019_conexs_newcastle:ex3 [2019/09/10 14:50] – [MgO] abussy | ||
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- | In this exercise we are going to compute near-edge X-ray absorption spectra of bulk MgS and MgO, performing all-electron calculations with GAPW method, using the Transition Potential and $\Delta$SCF approaches. Our goal is to identify differences in the electronic structure, and as a consequence in the K-edge absorption spectrum, of the magnesium due to different anions. We are also going to analyze the influence of basis set quality in the calculations. | + | In this exercise we are going to compute near-edge X-ray absorption spectra of bulk MgS and MgO, performing all-electron calculations with GAPW method, using the Transition Potential and $\Delta$SCF approaches. Our goal is to identify differences in the electronic structure, and as a consequence in the K-edge absorption spectrum, of the magnesium due to the different anions |
Before starting, it is recommended to create one directory for each system (MgO and MgS) and, within the system' | Before starting, it is recommended to create one directory for each system (MgO and MgS) and, within the system' | ||
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cp2k prints out the coordinates for each step of the calculation (they are indicated in the file by the index i, right below the number of atoms), so in order to use the optimized geometry in the following calculations, | cp2k prints out the coordinates for each step of the calculation (they are indicated in the file by the index i, right below the number of atoms), so in order to use the optimized geometry in the following calculations, | ||
- | It is also important to check for warnings in your output file. In the end of the output | + | It is also important to check for warnings in your output file. In the end of the file you can find the following banner: |
< | < | ||
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As an output you are going to get two files: '' | As an output you are going to get two files: '' | ||
- | In order to obtain the spectrum for atom 2, you can open the file '' | + | In order to obtain the spectrum for atom 2, you can open the file '' |
absorption spectrum. | absorption spectrum. | ||
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in the output file. The energy is given in Hartree, and to convert it to electron volts multiply the value by 27.211. This is the energy of the first transition, and you can use this value to rigidly shift your absorption spectrum. | in the output file. The energy is given in Hartree, and to convert it to electron volts multiply the value by 27.211. This is the energy of the first transition, and you can use this value to rigidly shift your absorption spectrum. | ||
- | =====Part 4: Changing basis-set===== | + | =====Part 4: Changing basis set===== |
Before performing the XAS calculations for the MgO system and compare the Mg absorption spectra, you can try to change the basis set you are using to run the absorption calculations to analyze differences it can bring to the description of the process. Try to perform the calculations using: | Before performing the XAS calculations for the MgO system and compare the Mg absorption spectra, you can try to change the basis set you are using to run the absorption calculations to analyze differences it can bring to the description of the process. Try to perform the calculations using: |
exercises/2019_conexs_newcastle/ex3.txt · Last modified: 2020/08/21 10:15 by 127.0.0.1