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* fixed laplacian of aos * corrected the laplacians of aos * added dft_one_e * added new feature for new dft functionals * changed the configure to add new functionals * changed the configure * added dft_one_e/README.rst * added README.rst in new_functionals * added source/programmers_guide/new_ks.rst * Thesis Yann * Added gmp installation in configure * improved qp_e_conv_fci * Doc * Typos * Added variance_max * Fixed completion in qp_create * modif TODO * fixed DFT potential for n_states gt 1 * improved pot pbe * trying to improve sr PBE * fixed potential pbe * fixed the vxc smashed for pbe sr and normal * Comments in selection * bug fixed by peter * Fixed bug with zero beta electrons * Update README.rst * Update e_xc_new_func.irp.f * Update links.rst * Update quickstart.rst * Update quickstart.rst * updated cipsi * Fixed energies of non-expected s2 (#9) * Moved diag_algorithm in Davdison * Add print_ci_vector in tools (#11) * Fixed energies of non-expected s2 * Moved diag_algorithm in Davdison * Fixed travis * Added print_ci_vector * Documentation * Cleaned qp_set_mo_class.ml * Removed Core in taskserver * Merge develop-toto and manus (#12) * Fixed energies of non-expected s2 * Moved diag_algorithm in Davdison * Fixed travis * Added print_ci_vector * Documentation * Cleaned qp_set_mo_class.ml * Removed Core in taskserver * Frozen core for heavy atoms * Improved molden module * In sync with manus * Fixed some of the documentation errors * Develop toto (#13) * Fixed energies of non-expected s2 * Moved diag_algorithm in Davdison * Fixed travis * Added print_ci_vector * Documentation * Cleaned qp_set_mo_class.ml * Removed Core in taskserver * Frozen core for heavy atoms * Improved molden module * In sync with manus * Fixed some of the documentation errors * Develop manus (#14) * modified printing for rpt2 * Comment * Fixed plugins * Scripting for functionals * Documentation * Develop (#10) * fixed laplacian of aos * corrected the laplacians of aos * added dft_one_e * added new feature for new dft functionals * changed the configure to add new functionals * changed the configure * added dft_one_e/README.rst * added README.rst in new_functionals * added source/programmers_guide/new_ks.rst * Thesis Yann * Added gmp installation in configure * improved qp_e_conv_fci * Doc * Typos * Added variance_max * Fixed completion in qp_create * modif TODO * fixed DFT potential for n_states gt 1 * improved pot pbe * trying to improve sr PBE * fixed potential pbe * fixed the vxc smashed for pbe sr and normal * Comments in selection * bug fixed by peter * Fixed bug with zero beta electrons * Update README.rst * Update e_xc_new_func.irp.f * Update links.rst * Update quickstart.rst * Update quickstart.rst * updated cipsi * Fixed energies of non-expected s2 (#9) * Moved diag_algorithm in Davdison * some modifs * modified gfortran_debug.cfg * fixed automatization of functionals * modified e_xc_general.irp.f * minor modifs in ref_bitmask.irp.f * modifying functionals * rs_ks_scf and ks_scf compiles with the automatic handling of functionals * removed prints * fixed configure * fixed the new functionals * Merge toto * modified automatic functionals * Changed python into python2 * from_xyz suppressed * Cleaning repo * Update README.md * Update README.md * Contributors * Update GITHUB.md * bibtex
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95 lines
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============================================
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Developping new functionals for KS or RS-DFT
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============================================
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The very basics
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===============
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To develop new functionals for |DFT| (or |RSDFT|) to be used in the SCF programs (:ref:`ks_scf` or :ref:`rs_ks_scf` ) or in multi-configurational |RSDFT| (see `<https://gitlab.com/eginer/qp_plugins_eginer>`_), you need to specify, at the end of the day, two things:
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* *exchange/correlation* **energy functionals** used to compute the **energy**
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* *exchange/correlation* **potentials** for (alpha/beta electrons) used to **optimize the wave function**
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The providers to define such quantities, and then used by all the all the |DFT| programs, are (see :ref:`module_dft_one_e`):
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* :c:data:`energy_x` and :c:data:`energy_c` : the *exchange* and *correlation* energy functionals (see :file:`e_xc_genera l.irp.f`)
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* :c:data:`potential_x_alpha_ao` and :c:data:`potential_x_beta_ao` : the exchange potential for alpha/beta electrons on the |AO| basis (se e :file:`pot_general.irp.f`)
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* :c:data:`potential_c_alpha_ao` and :c:data:`potential_c_beta_ao` : the correlation potential for alpha/beta electrons on the |AO| basis ( see :file:`pot_general.irp.f`)
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From the |AO| basis, the providers for the exchange/correlation potentials of alpha/beta electrons on the |MO| basis are automatically obtained by a |AO| --> |MO| transformation.
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So, at the end of the day, adding a new functional consists only in **setting a new value to these providers**.
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The general philosphy
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---------------------
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The directory **functionals** contains only files ending with .irp.f whose name being the name of a specific functional.
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All files in *a_functional*.irp.f **must** contain **at least** the following providers
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* :c:data:`energy_x_a_functional` and :c:data:`energy_c_a_functional` which are of course the exchange and correlation energies
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* :c:data:`potential_x_alpha_ao_a_functional` and :c:data:`potential_x_beta_ao_a_functional` which are the exchange alpha/beta potentials
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* :c:data:`potential_c_alpha_ao_a_functional` and :c:data:`potential_c_beta_ao_a_functional` which are the correlation alpha/beta potentials
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For instance, the file :file:`sr_lda.irp.f` contains the following providers
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* :c:data:`energy_x_sr_lda` and :c:data:`energy_c_sr_lda` which are of course the exchange and correlation energies
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* :c:data:`potential_x_alpha_ao_sr_lda` and :c:data:`potential_x_beta_ao_sr_lda` which are the exchange alpha/beta potentials
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* :c:data:`potential_c_alpha_ao_sr_lda` and :c:data:`potential_c_beta_ao_sr_lda` which are the correlation alpha/beta potentials
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Therefore, if you want to develop a new functional, just design a provider
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To use a functional
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Using the density for DFT calculations in the |QP|
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==================================================
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Different ways of defining the density for the DFT
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--------------------------------------------------
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There are many ways of defining a density, and the keyword to define it is :option:`density_for_dft density_for_dft`.
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Here are the following options for that keyword:
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* "KS" : density is obtained from **a single Slater determinant**
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* "WFT" : density is obtained from **the wave function** which is stored in the |EZFIO| data base
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* "input_density" : a one-body density matrix on the |MO| basis is read from the |EZFIO| data base, and the density is built from there (see :c:data:`data_one_e_dm_alpha_mo`)
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* "damping_rs_dft" : damped density between "WFT" and "input_density" with the damping factor :option:`density_for_dft damping_for_rs_dft`.
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.. note::
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If an |MO| basis is already defined in the |EZFIO| data base, the one-body density matrices will be defined
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according to this |MO| basis. For instance, if "KS", the density constructed will be density of a single Slater
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determinant built with the current |MO| basis stored in the |EZFIO| data base.
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Once that you have defined how to define the density, you can easily access to the providers associated to it.
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Value of the density and its gradients in real space
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----------------------------------------------------
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The density and its gradients evaluated on all grid points are (see :ref:`module_dft_utils_in_r`):
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* :c:data:`one_e_dm_alpha_at_r` and :c:data:`one_e_dm_beta_at_r` : alpha/beta density at grid points
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* :c:data:`one_e_dm_and_grad_alpha_in_r`, :c:data:`one_e_dm_and_grad_beta_in_r`: alpha/beta gradients (and densities)
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If you want to evaluate the density and its gradients at a given point in space, please refer to:
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* :c:func:`density_and_grad_alpha_beta_and_all_aos_and_grad_aos_at_r`
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If you use these *providers* and subroutines, the density computed will be coherent with the choice of density that you specified
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with :option:`density_for_dft density_for_dft`, and it will impact automatically the general providers of :ref:`module_dft_one_e`.
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