exercises:2017_uzh_cp2k-tutorial:wfc
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exercises:2017_uzh_cp2k-tutorial:wfc [2017/06/28 14:54] – vrybkin | exercises:2017_uzh_cp2k-tutorial:wfc [2017/07/07 14:35] – [1. Task: Benzene dimer MP2 binding energy] vrybkin | ||
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- | In order to go beyond GGA and hybrid DFT, one option is to use wave function correlation methods. Recently, second-order Møller-Plesset perturbation theory (MP2) and random phase approximation (RPA) have been added to CP2K [[doi> | + | In order to go beyond GGA and hybrid DFT, one option is to use wave function correlation methods. Recently, second-order Møller-Plesset perturbation theory (MP2) and random phase approximation (RPA) have been added to CP2K . The implementations are aimed at condensed phase calculations, |
- | However, significant computational resources are needed for the condensed phase calculations. Therefore, we will perform the gas phase calculations in this tutorial, even though RI-GPW is not very efficient in this case. | + | However, significant computational resources are needed for the condensed phase calculations |
+ | |||
+ | **Some references: | ||
+ | |||
+ | MP2 and RPA energies implementations in CP2K: | ||
+ | |||
+ | MP2 forces: [[doi> | ||
+ | |||
+ | Cubic scaling RPA implementation: | ||
+ | |||
+ | **Since the correlated wave function calculations are expensive, please use 4 cores for execution (with one OMP thread): | ||
+ | < | ||
+ | mpirun -np 4 -x OMP_NUM_THREADS=1 | ||
+ | </ | ||
===== 1. Task: Benzene dimer MP2 binding energy ===== | ===== 1. Task: Benzene dimer MP2 binding energy ===== | ||
- | 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 necessary | + | 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 |
- | 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 | ||
+ | </ | ||
+ | The last number in the line is the real time of execution. | ||
===== 2. Task: Benzene monomer RPA energy: frequency integration ===== | ===== 2. Task: Benzene monomer RPA energy: frequency integration ===== | ||
- | RPA is HFX+RPA correlation. It can be performed with HFX orbitals and eigenvalues, | + | RPA is HFX+RPA correlation. It can be performed with HFX orbitals and eigenvalues, |
Here, we look at the convergence of the RPA energy as a function of the number of integration points ('' | Here, we look at the convergence of the RPA energy as a function of the number of integration points ('' | ||
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====== Required files ====== | ====== Required files ====== | ||
+ | Input files and a wave function restart file can be found in the archive: {{ : | ||
input file for an RI-MP2 calculation on a benzene dimer | input file for an RI-MP2 calculation on a benzene dimer | ||
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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