EPW accuracy on various quantities

Some physical quantities are more sensitive to numerical instabilities than other. Below is a list of quantities tested by the EPW Test Farm and their related accuracies.

Note that this is an upper bounds and show the maximum variation on a quantity due to different compiler, hardware, libraries, level of optimization and parallelism.

Physical quantityAbsolute errorRelative error [in %]Benchmark valueSlaveNote
Eigenenergy (eV)0.0010.5-0.0219 (epw_soc)EPW-farmer_gcc485stable
Re[Sigma] (meV)0.022.0-982.600493 (epw_soc)EPW-farmer_gcc485stable
Im[Sigma] (meV)0.040.041858.014377 (epw_soc)EPW-farmer_gcc485stable
Z0.080.08-11.665563 (epw_soc)EPW-farmer_gcc485stable
PH lamda (lambda)0.000010.001stable
PH lamda (lambda_tr)0.000010.01stable
El lamda (lam)0.000013.0-0.00015 (epw_base)EPW-farm2_pgi15stable
Integrated lamda0.00010.020.6690848 (epw_soc)EPW-farm2_pgi15stable
Integrated lamda TR3100.02.7783115 (epw_soc)EPW-farm2_intel13bug
Ph gamma (meV)0.008900-0.001178 (epw_soc)EPW-farm2_intel13stable
Ph freq (meV)0.0050.05104.4255 (epw_trev)desktopstable
logavg for Tc0.000010.20.005807 (epw_trev)EPW-farmer4_gcc485_openblasstable
l_a2F for Tc0.0010.20.0838588 (epw_trev)EPW-farm2_intel13stable
Fermi level (eV)0.000010.001stable
lambda_max0.00050.015.164161 (epw_super)desktopstable
lambda_k_max0.00010.011.510491 (epw_super)desktopstable
Electron-phonon coupling strength0.00050.050.939445 (epw_super)desktopstable
Allen-Dynes Tc (K)0.020.0531.8408371 (epw_super)EPW-farm2_intel13stable
BCS superconducting gap0.00010.050.0048291 (epw_super)EPW-farm2_intel13stable

The Benchmark value is the value from the tests that lead to the largest error. In parenthesis is the name of the test from the test suite.

If you want to run the test yourself, you can do so by going to

cd espresso/test-suite/

Then type

make prolog

to generate the userconfig file.

You can then run an epw test in sequential by doing

make run-custom-test testdir=epw_base

and in parallel by doing

make run-custom-test-parallel testdir=epw_base