Added abinit_quickstart.

tutorials/part2/01_abinit_quickstart/abinit_quickstart.ipynb

+%% Cell type:markdown id:exempt-cloud tags:
+
+# Abinit - quickstart
+
+https://abinit.github.io/abipy/flow_gallery/run_sic_relax.html#sphx-glr-flow-gallery-run-sic-relax-py
+
+%% Cell type:code id:necessary-budapest tags:
+
+``` python
+!abicheck.py
+```
+
+%% Cell type:markdown id:chronic-invention tags:
+
+## Relaxation Flow
+
+This example shows how to build a very simple Flow for the structural relaxation of SiC. One could use a similar logic to perform multiple relaxations with different input parameters…
+
+
+%% Cell type:code id:handmade-dividend tags:
+
+``` python
+import abipy.abilab as abilab
+import abipy.data as data
+import abipy.flowtk as flowtk
+
+
+def build_flow(workdir):
+
+    pseudos = data.pseudos("14si.pspnc", "6c.pspnc")
+    structure = data.structure_from_ucell("SiC")
+
+    # Initialize the input
+    relax_inp = abilab.AbinitInput(structure, pseudos=pseudos)
+
+    # Set variables
+    relax_inp.set_vars(
+        ecut=20,
+        paral_kgb=1,
+        iomode=3,
+        # Relaxation part
+        ionmov=2,
+        optcell=1,
+        strfact=100,
+        ecutsm=0.5,       # Important!
+        dilatmx=1.15,     # Important!
+        toldff=1e-6,
+        tolmxf=1e-5,
+        ntime=100,
+    )
+
+    # K-points sampling
+    shiftk = [
+        [0.5,0.5,0.5],
+        [0.5,0.0,0.0],
+        [0.0,0.5,0.0],
+        [0.0,0.0,0.5]
+    ]
+    relax_inp.set_kmesh(ngkpt=[4, 4, 4], shiftk=shiftk)
+
+    # Initialize the flow
+    flow = flowtk.Flow(workdir)
+
+    # Register the task.
+    flow.register_relax_task(relax_inp)
+
+    return flow
+```
+
+%% Cell type:markdown id:related-music tags:
+
+Build and run the flow:
+
+%% Cell type:code id:steady-fellowship tags:
+
+``` python
+flow = build_flow('flow_sic_relax')
+flow.rmtree()
+
+scheduler = flow.make_scheduler()
+scheduler.start()
+```
+
+%% Cell type:markdown id:confirmed-space tags:
+
+To visualize the evolution of the lattice parameters during the structura relaxation use:
+
+%% Cell type:code id:raising-valuable tags:
+
+``` python
+abifile = abilab.abiopen('flow_sic_relax/w0/t0/outdata/out_HIST.nc')
+abifile.plot();
+```
+
+%% Cell type:code id:changing-bennett tags:
+
+``` python
+```
+
+%% Cell type:code id:passing-mineral tags:
+
+``` python
+```
+
+%% Cell type:code id:prescribed-mexico tags:
+
+``` python
+```