From 6e131190b0b56e87fb003c60aa88384f8569a4bd Mon Sep 17 00:00:00 2001
From: Johanna <johanna@zijderveld.de>
Date: Fri, 12 Apr 2024 12:23:12 +0200
Subject: [PATCH] add vectorized tb2kham function
---
codes/tb/transforms.py | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
diff --git a/codes/tb/transforms.py b/codes/tb/transforms.py
index 20e7a4a..4bfe6b3 100644
--- a/codes/tb/transforms.py
+++ b/codes/tb/transforms.py
@@ -3,6 +3,43 @@ from scipy.fftpack import ifftn
import itertools as it
+def tb2khamvector(h_0, nK, ndim):
+ """
+ Real-space tight-binding model to hamiltonian on k-space grid.
+
+ Parameters
+ ----------
+ h_0 : dict
+ A dictionary with real-space vectors as keys and complex np.arrays as values.
+ nK : int
+ Number of k-points along each direction.
+ ndim : int
+ Number of dimensions.
+
+ Returns
+ -------
+ ndarray
+ Hamiltonian evaluated on a k-point grid.
+
+ """
+
+ ks = np.linspace(-np.pi, np.pi, nK, endpoint=False)
+ ks = np.concatenate((ks[nK // 2 :], ks[: nK // 2]), axis=0) # shift for ifft
+ kgrid = np.meshgrid(ks, ks, indexing="ij")
+
+ num_keys = len(list(h_0.keys()))
+ tb_array = np.array(list(h_0.values()))
+ keys = np.array(list(h_0.keys()))
+
+ k_dependency = np.exp(-1j * np.tensordot(keys, kgrid, 1))[
+ (...,) + (np.newaxis,) * 2
+ ]
+ tb_array = tb_array.reshape(
+ np.concatenate(([num_keys], [1] * ndim, tb_array.shape[1:]))
+ )
+ return np.sum(tb_array * k_dependency, axis=0)
+
+
def tb2kfunc(h_0):
"""
Fourier transforms a real-space tight-binding model to a k-space function.
--
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