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Lorenzo Paulatto lorenzo.paulatto at impmc.upmc.fr
Mon Jul 25 21:25:31 CEST 2016

Dear Quantum-ESPRESSO users,

I'm very proud to announce the first public release of a new code in the
Quantum-ESPRESSO family. The *D3Q* code can compute the third derivative of
the total energy with respect to three generic phonons. The code is much
more efficient than any finite differences code, using the 2n+1 theorem on
top of density functional perturbation theory (DFPT). The current release
can treat:


   insulators, semiconductors and metals

   LDA and GGA functionals


   norm conserving pseudopotentials

The third derivatives aren't of much use by themselves, that's why we
bundle the D3Q code with the *thermal2* suite of codes to compute intrinsic
phonon-phonon interactions and solve the Boltzmann transport equation. This
suite of codes can compute:


   *phonon lifetime and linewidth from ph-ph interaction*

   phonon self-energy from the Bubble (thid order) diagram

   final state decomposition of phonon decay process, over energy and

   phonon spectral function

   *thermal conductivity in the single mode approximation* (SMA) of the
   linearized Boltzmann Transport Equation (BTE)

   *thermal conductivity with exact solution of the BTE*. This solution is
   computed using a variational form, minimized via a preconditioned conjugate
   gradient algorithm: guaranteed to converge, usually in less than 10

   inclusion of isotopic disorder and mass substitution defects

   effect of grain size and finite transverse dimension (e.g. nanotubes)
   using the Casimir formalism

   simultaneous calculation of many temperatures/smearings

   in addition to using our force constants from DFPT, we support importing
   3-body force constants computed via finite differences with the
   thirdorder.py code (experimental!)

   parallel computing implemented with MPI (with great scalability up to
   thousand of CPUs) and OpenMP (optimal for memory reduction)

You can download the code (to be compiled together with QE 5.4.0) including
extensive examples, tutorials and manuals from the project website on the
qe-forge: http://www.qe-forge.org/gf/project/d3q/

We have also set up a specific mailing list for users help requests,
available at: http://www.qe-forge.org/mailman/listinfo/d3q-users

The main code authors for the D3Q and thermal2 codes are Lorenzo Paulatto,
Michele Lazzeri, Giorgia Fugallo, Andrea Cepellotti, Tobias Wassmann,
Francesco Mauri. Contributions, in the form of code, testing or insight,
have also come from Nicola Marzari, Ion Errea, Raffaello Bianco, Maksim
Markov, Nathalie Vast, Davide Campi, Guilherme Ribeiro. The original d3.x
code, on which the current one is based, was also written by Stefano de

Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
www:   http://www-int.impmc.upmc.fr/~paulatto/
mail:  23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05
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