: an ab-initio tool for excited state calculations
Properties
Theory&approximations
GPL:
Quasiparticles
Optical absorption
Electron energy loss
Dynamical polarizability
Many-Body Perturbation Theory
Time-dependent density functional theory
Develop/pre-GPL:
magnetic properties
non-equilibrium dynamics
total energies
electron-phonon effects
Interfaces
Planewave- Pseudopotential codes:
Support & reach-out
Dedicated users forum
Online documentation/tutorials
Schools & workshops
Developers
Community
about 170 users
(mostly from EU, USA, China)
Publications
more than 120 publications
www.yambo-code.org
: an ab-initio tool for R&D
Material Science
Nano Science
applications to
e.g. photovoltaics,
lithium batteries,
microelectronics
Biology
applications to
e.g. nanophotonics,
nanoelectronics
Physics
studies of
photoactive
molecules
and molecular
complexes
fundamental
understanding
of physical
processes
www.yambo-code.org
: the physics behind the code
Key quantity: Density response
Describe response
of electronic density
to an external perturbation
Perturbation
Unperturbed
system
Perturbed
system
described by its
electronic density:
change in the
electronic density:
www.yambo-code.org
Relative Frequency
: the physics behind the code
Experimental
measurements
Calculate density
response
Relative Frequency
Electron Energy Loss (eV)
Calculated
spectra
Electron Energy Loss (eV)
www.yambo-code.org
: how to calculate the response function
Step 1: Build-up independent particles response
function
electrons
space of phases
describes the transitions
between the two spaces
holes
space of phases
Typical dimensions of phase space:
www.yambo-code.org
: how to calculate the response function
Step 2: Towards the "real" response function
+
Independent particles
Interaction between elements
of the space of phases
RPA
TDLDA
BSE
"real"
level of approximation/correlation
www.yambo-code.org
: how the code is parallelized
Step 1: Build up of
On the space of phases:
multilevel, flexible, general
Step 2:
Using SCALAPACK library
www.yambo-code.org
: tests of performance/parallelization
Test case
Si100 c(4x4) slab, 16 layers
64 atoms
30Ry cutoff = 35000 Gs in wfc.
20 k-points, 21 q-points.
350 bands, of which 128 occupied.
Architecture
IBM SP6@ CINECA
Peak computing power:101 Tflops
- 5376 cores in total
- 128Gb of shared memory/node
- Simultaneous Multi-Threading
- Infiniband 4x DDR network
Resources for this job:
max. 64 cpus with SMT
ConsumableMemory=4.4Gb
Compilation
export CC=xlc_r
export FC=xlf95_r
export FCFLAGS='-O2 -q64 -qstrict -qarch=pwr6 -qtune=pwr6 -qmaxmem=-1 -qsuffix=f=f'
./configure --build=powerpc-ibm --with-fftw=/cineca/prod/libraries/fftw/3.2.2/xl--10.1/lib
--with-netcdf-lib=/cineca/prod/libraries/netcdf/4.0.1/xl--10.1/lib
--with-scalapack=/gpfs/prod/libraries/scalapack/1.8.0/xl--10.1/lib/
--with-blacs=/gpfs/prod/libraries/blacs/1.1/xl--10.1/lib/
yambo v3.2.4 r20: avalaible from qe-forge svn repository
www.yambo-code.org
: tests of performance/parallelization
Steps:
Build-up of
Inversion
(SCALAPACK)
www.yambo-code.org