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114 lines
3.1 KiB
Markdown
114 lines
3.1 KiB
Markdown
# Orbital localisation
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To localize the MOs:
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```
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qp run localization
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```
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By default, the different orbital classes are automatically set by splitting
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the orbitales in the following classes:
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- Core -> Core
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- Active, doubly occupied -> Inactive
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- Active, singly occupied -> Active
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- Active, empty -> Virtual
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- Deleted -> Deleted
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The orbitals will be localized among each class, excpect the deleted ones.
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If you want to choose another splitting, you can set
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```
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qp set mo_localization auto_mo_class false
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```
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and define the classes with
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```
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qp set_mo_class -c [] -a [] -v [] -i [] -d []
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```
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for more information
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```
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qp set_mo_class -q
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```
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We don't care about the name of the
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mo classes. The algorithm just localizes all the MOs of
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a given class between them, for all the classes, except the deleted MOs.
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If you are using the last option don't forget to reset the initial mo classes
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after the localization.
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Before the localization, a kick is done for each mo class
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(except the deleted ones) to break the MOs. This is done by
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doing a given rotation between the MOs.
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This feature can be removed by setting:
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```
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qp set localization kick_in_mos false
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```
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and the default angle for the rotation can be changed with:
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```
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qp set localization angle_pre_rot 1e-3 # or something else
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```
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After the localization, the MOs of each class (except the deleted ones)
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can be sorted between them using the diagonal elements of
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the fock matrix with:
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```
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qp set localization sort_mos_by_e true
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```
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You can check the Hartree-Fock energy before/during/after the localization
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by putting (only for debugging):
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```
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qp set localization debug_hf true
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```
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## Foster-Boys & Pipek-Mezey
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Foster-Boys:
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```
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qp set localization localization_method boys
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```
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Pipek-Mezey:
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```
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qp set localization localization_method pipek
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```
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# Break the spatial symmetry of the MOs
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This program work exactly as the localization.
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To break the spatial symmetry of the MOs:
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```
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qp run break_spatial_sym
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```
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The default angle for the rotations is too big for this kind of
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application, a value between 1e-3 and 1e-6 should break the spatial
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symmetry with just a small change in the energy:
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```
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qp set localization angle_pre_rot 1e-3
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```
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# With or without hessian + trust region
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With hessian + trust region
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```
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qp set localization localisation_use_hessian true
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```
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It uses the trust region algorithm with the diagonal of the hessian of the
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localization criterion with respect to the MO rotations.
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Without the hessian and the trust region
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```
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qp set localization localisation_use_hessian false
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```
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By doing so it does not require to store the hessian but the
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convergence is not easy, in particular for virtual MOs.
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It seems that it not possible to converge with Pipek-Mezey
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localization with this approach.
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# Parameters
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Some other parameters are available for the localization (qp edit for more details).
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# Tests
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```
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qp test
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```
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# Org files
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The org files are stored in the directory org in order to avoid overwriting on user changes.
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The org files can be modified, to export the change to the source code, run
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```
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./TANGLE_org_mode.sh
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mv *.irp.f ../.
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```
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