Libra news - 12/13/2019

[Alexey Akimov]

Hi everyone,

You may not be hearing from us too often, but a lot of things is going on with Libra development. Here are some recent news:

1) We have reached a remarkable milestone - 1000 commits on the development branch. At this point, it made a lot of sense to merge the development branch into the master branch, so the two are even. This version is also tagged as v4.2.0 for easy referencing.

2) At a bigger scale:

- we are now fully switched to Python 3, no more Python 2 support;

- the dynamics code is significantly cleaned up and refactored for better modularity;

- we started adding the HDF5 support, so no more tons of small files or operating system memory limitations;

- completely revised Tutorials on the quantum-classical methods (/notebooks/Example16_Dynamics/)

- for a while, we have been keeping track of the versions via tagging, so you can now refer to particular versions of the code by selecting the desired tag number

- the Python codes are well-documented, and the auto-generated documentation is updated on the Libra webpage: https://quantum-dynamics-hub.github.io/libra/documentation.html

3) Current methodologies:

- propagation schemes: Ehrenfest, adiabatic dynamics, TSH

- adiabatic or diabatic representation - at various levels (mix and match, depending on the data availability/needs)

- surface hopping schemes: FSSH, GFSH, MSSH, Landau-Zener/Belyaev-Lebedev

- decoherence schemes: SDM, DISH, instantaneous decoherence (3 flavors)

- dephasing times: user-defined, energy-based Granucci-Persico/Truhlar, via energy gap fluctuations, dephasing-informed corrections

- state tracking & phase corrections

- velocity rescaling: none, energy-based, along arbitrary vectors (derivative couplings, gradient differences, etc.)

- handling frustrated hops: reversal/no reversal

- neglect of back-reaction approximation (NBRA) or not

- hop acceptance schemes: energy-based, Boltzmann or Maxwell-Boltzmann factors

- Boltzmann-corrected Ehrenfest within the NBRA

- user-defined computation of Hamiltonians (including via reading data files as formerly done in Pyxaid)

- various schemes to initialize nuclear/electronic DOFs

- interfaces with electronic structure packages: ErgoSCF, DFTB+, Quantum Espresso, etc.

Best,

Alexey