Adding doc dumped from web and 2 example scripts for ASE

examples/crystal.py

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+# Import the basic libraries
+
+# ASE system
+import ase
+from ase import Atom, Atoms
+from ase import io
+from ase.lattice.spacegroup import crystal
+
+# Spacegroup/symmetry library
+from pyspglib import spglib
+
+# The qe-util package
+from qeutil import QuantumEspresso
+
+# iPython utility function
+from IPython.core.display import Image
+
+# Configure qe-util for local execution of the Quantum Espresso on four processors
+# QuantumEspresso.pw_cmd='mpiexec -n 4 pw.x < pw.in > pw.out'
+
+a=4.3596                                         # Lattice constant in Angstrom
+cryst = crystal(['Si', 'C'],                     # Atoms in the crystal
+                [(0, 0, 0), (0.25, 0.25, 0.25)], # Atomic positions (fractional coordinates)
+                spacegroup=216,                  # International number of the spacegroup of the crystal
+                cellpar=[a, a, a, 90, 90, 90])   # Unit cell (a, b, c, alpha, beta, gamma) in Angstrom, Degrees
+
+# Write the image to disk file
+ase.io.write('crystal.png',       # The file where the picture get stored
+             cryst,               # The object holding the crystal definition
+             format='png',        # Format of the file
+             show_unit_cell=2,    # Draw the unit cell boundaries
+             rotation='115y,15x', # Rotate the scene by 115deg around Y axis and 15deg around X axis
+             scale=30)            # Scale of the picture
+
+# Display the image
+Image(filename='crystal.png')
+
+print 'Space group:', spglib.get_spacegroup(cryst)
+
+# Create a Quantum Espresso calculator for our work. 
+# This object encapsulates all parameters of the calculation, 
+# not the system we are investigating.
+qe=QuantumEspresso(label='SiC',                    # Label for calculations
+                       wdir='.',                   # Working directory
+                       pseudo_dir='/usr/share/espresso/pseudo',   # Directory with pseudopotentials
+                       kpts=[2,2,2],               # K-space sampling for the SCF calculation
+                       xc='pz',                    # Exchange functional type in the name of the pseudopotentials
+                       pp_type='vbc',              # Variant of the pseudopotential
+                       pp_format='UPF',            # Format of the pseudopotential files
+                       ecutwfc=20,                 # Energy cut-off (in Rydberg)
+                       use_symmetry=False, procs=8)          # Use symmetry in the calculation ?
+
+print qe.directory
+
+# Assign the calculator to our system
+cryst.set_calculator(qe)
+
+# Run the calculation to get stress tensor (Voigt notation, in eV/A^3) and pressure (in kBar)
+print "Stress tensor   (Voigt notation eV/A^3):", cryst.get_stress()
+# print "External pressure                (kBar):", cryst.get_isotropic_pressure(cryst.get_stress())*1e-3
+
+print 'All done and functional: QE, stress.'

examples/phonons.py

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+from ase.lattice import bulk
+from ase.dft.kpoints import ibz_points, get_bandpath
+from ase.phonons import Phonons
+
+# The qe-util package
+from qeutil import QuantumEspresso
+
+# Setup crystal and EMT calculator
+atoms = bulk('Al', 'fcc', a=4.05)
+
+qe=QuantumEspresso(label='Al',                    # Label for calculations
+                       wdir='.',                   # Working directory
+                       pseudo_dir='/usr/share/espresso/pseudo',   # Directory with pseudopotentials
+                       kpts=[2,2,2],               # K-space sampling for the SCF calculation
+                       xc='pz',                    # Exchange functional type in the name of the pseudopotentials
+                       pp_type='vbc',              # Variant of the pseudopotential
+                       pp_format='UPF',            # Format of the pseudopotential files
+                       ecutwfc=15,                 # Energy cut-off (in Rydberg)
+                       occupations='smearing', 
+                       smearing='methfessel-paxton', 
+                       degauss=0.0198529,
+                       mixing_beta=0.7, mixing_mode = 'plain', diagonalization = 'cg',
+                       restart_mode='from_scratch', tstress=False,
+                       use_symmetry=False, procs=8)          # Use symmetry in the calculation ?
+
+print qe.directory
+
+# Assign the calculator to our system
+atoms.set_calculator(qe)
+
+ph = Phonons(atoms, qe, supercell=(2,2,2), delta=0.05)
+ph.run()
+# Read forces and assemble the dynamical matrix
+ph.read(acoustic=True)
+
+print 'All done and functional: QE, phonons.'