This is the Shirley Reduced Basis (SRB) version of Quantum Espresso.
The SRB is reduced order model for PWDFT that coarsely samples the BZ.
To use the SRB, add this namelist to your input files:
 &srb
  use_srb = .true.
 /
You also need to define Q_POINTS, which are the sparse BZ sample
used to build the basis (+ periodic mirrors specified by ntrans)  For
3D bulk systems, start with:
 Q_POINTS crystal
  7
  0.0 0.0 0.0 1.0
  0.5 0.0 0.0 1.0
  0.0 0.5 0.0 1.0
  0.0 0.0 0.5 1.0
  0.0 0.5 0.5 1.0
  0.5 0.5 0.0 1.0
  0.5 0.0 0.5 1.0

For 2D sheets in the x-y plane:
 Q_POINTS crystal
  7
  0.0  0.0  0.0 1.0
  0.25 0.0  0.0 1.0 
  0.5  0.0  0.0 1.0 
  0.75 0.0  0.0 1.0 
  0.0  0.25 0.0 1.0 
  0.0  0.5  0.0 1.0 
  0.0  0.75 0.0 1.0 

These can be tweaked based on the physics of the system.

_NOTE_
There is temporarily an additional constraint that the order in the 
ATOMIC_SPECIES and ATOMIC_POSITIONS cards are consistent.  For
example, this is OK:
 ATOMIC_SPECIES
  Zn 65.39  Zn.UPF
  Cu 63.546 Cu.UPF

 ATOMIC_POSITIONS crystal
  Zn  0.21780000  0.21780000  0.21780000
  Zn -0.21780000  0.00000000  0.00000000
  Cu -0.34400000 -0.34400000 -0.34400000

But this is not:
 ATOMIC_SPECIES
  Cu 63.546 Cu.UPF
  Zn 65.39  Zn.UPF

 ATOMIC_POSITIONS crystal
  Zn  0.21780000  0.21780000  0.21780000
  Zn -0.21780000  0.00000000  0.00000000
  Cu -0.34400000 -0.34400000 -0.34400000

Nor is this:
 ATOMIC_SPECIES
  Zn 65.39  Zn.UPF
  Cu 63.546 Cu.UPF

 ATOMIC_POSITIONS crystal
  Zn  0.21780000  0.21780000  0.21780000
  Cu -0.34400000 -0.34400000 -0.34400000
  Zn -0.21780000  0.00000000  0.00000000


There are additional optional parameters:
 * basis_life (int) sets the number of SCF iterations each basis is
   used for.
   * Default: 1
   * Recommended: 3
 * ntrans(1:3) (int) defines the number of periodic mirrors of the
   unit BZ, [0:1]^3, in which to translate k-points.
   * Default: 1
   * Recommended: ntrans(i) = 0 for i without k-points, e.g. i=3 for x-y sheet
 * trace_tol (double) defines largest tolerated error in the norm of the
   overlap matrix composed of bands at the input q-points.  This is 
   analogous to the maximum variance removed in principal component analysis.
   Negative values are treated as zero.
   * Default: 1.D-7
   * Recommended: 1.D-7
 * max_basis_size (int) puts an upper limit on the size of the basis.
   Negative values are treated as infinity.
   * Default: -1
   * Recommended: -1 (use trace_tol instead)
 * rho_reduced (logical) specifies the use of the dense, reduced density
   matrix method, which faster when 4*nbnd*nq > nbasis
   * Default: .true.
   * Recommended: .true.
 * aux_tol (double) defines the largest tolerated error in the norm of the
   overlap matrix composed of projectors at the input k-points.  Similar
   to trace_tol, but for projectors and exact (no Shirley interpolation)
   * Default: 3.D-3
   * Recommended: 3.D-3
 * min_aux_size (integer) defines the minimum number of atoms per type
   for that type to use an auxilary basis.
   * Default: 16
   * Recommended: 16
 * freeze_basis (double) defines the energy convergence at which to stop
   updating the basis.  Negative values signal to use sqrt(conv_thr)
   * Default: -1
   * Recommended: -1
 * srb_debug (logical) specifies the inclusion of debugging checks, mostly
   in the procedure to build the basis
   * Default: .false.
   * Recommended: .false.
 * use_cuda (logical) specifies the use of GPU accelerated routines
   * Default: .false.
   * Recommended: .true. if you have GPU's in your system

----

This is the distribution of the Quantum ESPRESSO suite of codes (ESPRESSO: 
opEn-Source Package for Research in Electronic Structure, Simulation, 
and Optimization), promoted by the IOM-DEMOCRITOS National Simulation Center 
of the Italian CNR (http://www.democritos.it). 


Quick installation instructions for the impatient:
   ./configure [options]
   make all
("make" alone prints a list of acceptable targets). Binaries go in bin/.
For more information, see the general documentation in directory Doc/, 
package-specific documentation in */Doc/, and the web site
http://www.quantum-espresso.org/

All the material included in this distribution is free software;
you can redistribute it and/or modify it under the terms of the GNU
General Public License as published by the Free Software Foundation;
either version 2 of the License, or (at your option) any later version.

These programs are distributed in the hope that they will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
675 Mass Ave, Cambridge, MA 02139, USA.