exercises:2017_uzh_cp2k-tutorial:wfc
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exercises:2017_uzh_cp2k-tutorial:wfc [2017/07/07 14:18] – vrybkin | exercises:2017_uzh_cp2k-tutorial:wfc [2017/07/07 14:34] – [1. Task: Benzene dimer MP2 binding energy] vrybkin | ||
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Employ the provided input file to compute the benzene dimer binding energy. The provided dimer geometry is optimized already. To obtain the energy of the monomer, geometry optimization is in principle necessary, although the geometry of a benzene monomer must be close to the one in the dimer. This can be done by removing one of the benzene molecules editing the coordinates in the input. Perform a few optimization steps to see how much the energy changes and to calculate electron density (saved as .cube files) at the MP2 level. If energy does not change much, this means that the monomer structure is already close to the optimal. Compare the times needed for one geometry optimization step (energy+forces) for a monomer and energy for a dimer, as well as the relative timing for energy and forces evaluation for a monomer. | Employ the provided input file to compute the benzene dimer binding energy. The provided dimer geometry is optimized already. To obtain the energy of the monomer, geometry optimization is in principle necessary, although the geometry of a benzene monomer must be close to the one in the dimer. This can be done by removing one of the benzene molecules editing the coordinates in the input. Perform a few optimization steps to see how much the energy changes and to calculate electron density (saved as .cube files) at the MP2 level. If energy does not change much, this means that the monomer structure is already close to the optimal. Compare the times needed for one geometry optimization step (energy+forces) for a monomer and energy for a dimer, as well as the relative timing for energy and forces evaluation for a monomer. | ||
- | Topics: | + | During the optimization of benzene, one will calculate gradient which, in turn, requires density matrices. Hence, one can calculate electronic densities. Add the following to the '' |
- | * RI approach ('' | + | < |
- | * Wavelet solver ('' | + | & |
- | * gas phase HFX calculation | + | &END |
- | | + | </ |
+ | and the following lines to the '' | ||
+ | < | ||
+ | |||
+ | | ||
+ | &END | ||
+ | &END | ||
+ | </ | ||
+ | |||
+ | Importantly, during the force calculations one will have to solve the coupled-perturbed equations invoking exact exchange calculations. If there is enough memory we can reuse the integrals from the HF calculation by setting the following keyword in the '' | ||
+ | < | ||
+ | FREE_HFX_BUFFER .FALSE. | ||
+ | </ | ||
+ | |||
+ | Perform two optimizations setting **FREE_HFX_BUFFER** to **.TRUE.** and **.FALSE.**. Compare the overall timings and especially the times for performing Hartree-Fock exchange calculations: | ||
+ | < | ||
+ | integrate_four_center | ||
+ | </ | ||
===== 2. Task: Benzene monomer RPA energy: frequency integration ===== | ===== 2. Task: Benzene monomer RPA energy: frequency integration ===== | ||
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</ | </ | ||
- | During the optimization of benzene, one will calculate gradient which, in turn, requires density matrices. Hence, one can calculate electronic densities. Add the following to the ''& | ||
- | < | ||
- | & | ||
- | &END | ||
- | </ | ||
- | and the following lines to the ''& | ||
- | < | ||
- | |||
- | & | ||
- | &END | ||
- | &END | ||
- | </ | ||
- | Importantly, | ||
- | < | ||
- | FREE_HFX_BUFFER .FALSE. | ||
- | </ | ||
| |
exercises/2017_uzh_cp2k-tutorial/wfc.txt · Last modified: 2020/08/21 10:15 by 127.0.0.1