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mirror of https://github.com/triqs/dft_tools synced 2024-11-06 22:23:52 +01:00

[doc] added another faq

This commit is contained in:
Priyanka Seth 2015-05-04 14:48:22 +02:00
parent 0aed9c681f
commit f7c2298eed
3 changed files with 40 additions and 101 deletions

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@ -11,10 +11,14 @@ A hack solution is as follows:
3) `x lapw2 -almd -band`
4) `dmftproj -band` (add the fermi energy to file, it can be found by running `grep :FER *.scf`)
How do I do ..this..?
---------------------
How do I plot the output of `spaghettis`?
-----------------------------------------
This is how you do this.
In python, you can do the following for example. You should pass the name of
the file written out by the spaghettis function. Of course, you should change
the parameters as desired.
.. literalinclude:: plotting_spaghettis.py
Why is my calculation not working?
----------------------------------

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@ -0,0 +1,33 @@
from matplotlib import *
import matplotlib.pyplot as plt
import numpy as np
filename = 'spaghettis_to_plot.dat' # Name of file
emin = -1.0 # Minimum of energy range to plot
emax = 1.5 # Maximum of energy range to plot
zmin = 0.0 #z.min() # Minimum of colour range
zmax = 5.0 #z.max() # Maximum of colour range
kpos = [0, 50, 100, 150, 200] # Position of high-symmetry k-point
kname = ['M', 'G', 'X', 'Z', 'M'] # Name of high-symmetry k-point
b = np.loadtxt(filename)
n_k = int(b[:,0][-1] + 1)
mesh_size = len(b[:,0])/n_k
klist = b[:,0][::mesh_size]
elist = b[:,1][0:mesh_size]
x,y = np.meshgrid(klist,elist)
z = b[:,2].reshape(n_k,mesh_size)
fig, ax = plt.subplots()
p = ax.pcolormesh(x,y,z.T, cmap=cm.Blues, vmin=zmin, vmax=zmax)
cb = fig.colorbar(p, ax=ax)
ax.set_xlim(klist.min(),klist.max())
ax.set_ylim(emin,emax)
ax.hlines(0.0,0,n_k-1)
plt.title(filename,fontsize=24)
for i in kpos: ax.vlines(i,emin,emax,alpha=0.5)
plt.xticks(kpos,kname,fontsize=16)
plt.ylabel('Energy (%s)'%'eV', fontsize=18)
plt.yticks(fontsize=16)
plt.grid()
plt.savefig(''.join(kname)+'_'+filename.replace('dat','png'),bbox_inches='tight')

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@ -1,98 +0,0 @@
class function_template():
def old_fft(name, state=None):
"""This function does something.
:param name: The name to use.
:type name: str.
:param state: Current state to be in.
:type state: bool.
:returns: int -- the return code.
:raises: AttributeError, KeyError
"""
return 0
def fft(a, n=None, axis=-1):
"""
Compute the one-dimensional discrete Fourier Transform.
This function computes the one-dimensional *n*-point discrete Fourier
Transform (DFT) with the efficient Fast Fourier Transform (FFT)
algorithm [CT].
Parameters
----------
a : array_like
Input array, can be complex.
n : int, optional
Length of the transformed axis of the output.
If `n` is smaller than the length of the input, the input is cropped.
If it is larger, the input is padded with zeros. If `n` is not given,
the length of the input along the axis specified by `axis` is used.
axis : int, optional
Axis over which to compute the FFT. If not given, the last axis is
used.
Returns
-------
out : complex ndarray
The truncated or zero-padded input, transformed along the axis
indicated by `axis`, or the last one if `axis` is not specified.
Raises
------
IndexError
if `axes` is larger than the last axis of `a`.
See Also
--------
numpy.fft : for definition of the DFT and conventions used.
ifft : The inverse of `fft`.
fft2 : The two-dimensional FFT.
fftn : The *n*-dimensional FFT.
rfftn : The *n*-dimensional FFT of real input.
fftfreq : Frequency bins for given FFT parameters.
Notes
-----
FFT (Fast Fourier Transform) refers to a way the discrete Fourier
Transform (DFT) can be calculated efficiently, by using symmetries in the
calculated terms. The symmetry is highest when `n` is a power of 2, and
the transform is therefore most efficient for these sizes.
The DFT is defined, with the conventions used in this implementation, in
the documentation for the `numpy.fft` module.
References
----------
.. [CT] Cooley, James W., and John W. Tukey, 1965, "An algorithm for the
machine calculation of complex Fourier series," *Math. Comput.*
19: 297-301.
Examples
--------
>>> np.fft.fft(np.exp(2j * np.pi * np.arange(8) / 8))
array([ -3.44505240e-16 +1.14383329e-17j,
8.00000000e+00 -5.71092652e-15j,
2.33482938e-16 +1.22460635e-16j,
1.64863782e-15 +1.77635684e-15j,
9.95839695e-17 +2.33482938e-16j,
0.00000000e+00 +1.66837030e-15j,
1.14383329e-17 +1.22460635e-16j,
-1.64863782e-15 +1.77635684e-15j])
>>> import matplotlib.pyplot as plt
>>> t = np.arange(256)
>>> sp = np.fft.fft(np.sin(t))
>>> freq = np.fft.fftfreq(t.shape[-1])
>>> plt.plot(freq, sp.real, freq, sp.imag)
[<matplotlib.lines.Line2D object at 0x...>, <matplotlib.lines.Line2D object at
0x...>]
>>> plt.show()
In this example, real input has an FFT which is Hermitian, i.e., symmetric
in the real part and anti-symmetric in the imaginary part, as described in
the `numpy.fft` documentation.
"""
return 0