Basic structural implementation of diamond chain.

.gitignore

+### OS and IDE temporaries
+*.DS_Store
+.*~
+.*.swp
+
+## Latex temporaries
+*.aux
+*.lof
+*.log
+*.lot
+*.fls
+*.out
+*.toc
+*.fmt
+*.fot
+*.cb
+*.cb2
+*.bbl
+*.bcf
+*.blg
+*-blx.aux
+*-blx.bib
+
+### Python temporaries
+**/__pycache__/*
+*.py[cod]
+*.egg
+MANIFEST
+
+### Jupyter temporaries
+**/.ipynb_checkpoints
+
+### Compiled binaries
+*.so
+*.o
+*.a
+*.exe
+*.out
+
+### Testing and coverage reports
+htmlcov/
+.tox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+.hypothesis/
+

code/.ipynb_checkpoints/testing_ground-checkpoint.py

+sdf
\ No newline at end of file

code/modules/.ipynb_checkpoints/diamond_chain-checkpoint.py

+import kwant
+import numpy as np
+
+
+def diamond_chain_system(N_c, system_params):
+    '''
+    Create a diamond chain of trimer unit cells. Each atom of the trimer has two orbital angular momentum states, + and -
+          _______
+    ...  | C_i_+ |
+         | C_i_- |         ...
+        / ------- \ ______ /
+    ...           | A_i_+ | ...
+                  | A_i_- |
+        \ ______ / ------- \
+    ...  | B_i_+ |         ...
+         | B_i_- |
+          ------- 
+    
+    :param int N_c: number of unit cells to include in the cell
+    :param dict system_params: parameters
+    
+    :rtype kwant.system.FiniteSystem:
+    '''
+    
+    # make lattices and sublattices
+    lat = kwant.lattice.Polyatomic(prim_vecs = [[1,0],[0,1]], basis = [[1,0],[1,0], [0,-1],[0,-1], [0,1],[0,1]])
+    a_lat_pos, a_lat_neg, b_lat_pos, b_lat_neg, c_lat_pos, c_lat_neg = lat.sublattices
+    
+    #make builder and populate with onsite and hoppings
+    syst = kwant.Builder()
+    
+    
+    for i in range(N_c):
+        
+        #staggered point
+        sp = 2*i
+        
+        syst[a_lat_pos(sp,0)] = 0
+        syst[a_lat_neg(sp,0)] = 0
+        syst[b_lat_pos(sp,0)] = 0
+        syst[b_lat_neg(sp,0)] = 0
+        syst[c_lat_pos(sp,0)] = 0
+        syst[c_lat_neg(sp,0)] = 0
+        
+        if i < N_c - 1:
+        
+            
+            syst[c_lat_pos(sp+2,0)] = 0
+            syst[b_lat_pos(sp+2,0)] = 0
+            syst[c_lat_neg(sp+2,0)] = 0
+            syst[b_lat_neg(sp+2,0)] = 0
+
+            # + <--> + 
+            syst[a_lat_pos(sp,0), c_lat_pos(sp+2,0)] = 1
+            syst[a_lat_pos(sp,0), b_lat_pos(sp+2,0)] = 1
+
+            # - <--> -
+            syst[a_lat_neg(sp,0), c_lat_neg(sp+2,0)] = 1
+            syst[a_lat_neg(sp,0), b_lat_neg(sp+2,0)] = 1
+
+            # + <--> - 
+            syst[a_lat_pos(sp,0), b_lat_neg(sp+2,0)] = 1
+            syst[a_lat_neg(sp,0), b_lat_pos(sp+2,0)] = 1
+
+            # + <--> - hopping with phase
+            syst[a_lat_pos(sp,0), c_lat_neg(sp+2,0)] = 1
+            syst[a_lat_neg(sp,0), c_lat_pos(sp+2,0)] = 1
+            
+        # + <--> + 
+        syst[a_lat_pos(2*i,0), c_lat_pos(sp,0)] = 1
+        syst[a_lat_pos(2*i,0), b_lat_pos(sp,0)] = 1
+        # - <--> -
+        syst[a_lat_neg(2*i,0), c_lat_neg(sp,0)] = 1
+        syst[a_lat_neg(2*i,0), b_lat_neg(sp,0)] = 1
+        # + <--> - 
+        syst[a_lat_pos(2*i,0), c_lat_neg(sp,0)] = 1
+        syst[a_lat_neg(2*i,0), c_lat_pos(sp,0)] = 1
+        # + <--> - hopping with phase
+        syst[a_lat_pos(2*i,0), b_lat_neg(sp,0)] = 1
+        syst[a_lat_neg(2*i,0), b_lat_pos(sp,0)] = 1
+        
+    
+
+    
+    
+    return syst
+
+m = diamond_chain_system(10,None)
+
+kwant.plot(m)
+
+
+
+

code/modules/diamond_chain.py

+import kwant
+import numpy as np
+
+
+def diamond_chain_system(N_c, system_params):
+    '''
+    Create a diamond chain of trimer unit cells. Each atom of the trimer has two orbital angular momentum states, + and -
+          _______
+    ...  | C_i_+ |
+         | C_i_- |         ...
+        / ------- \ ______ /
+    ...           | A_i_+ | ...
+                  | A_i_- |
+        \ ______ / ------- \
+    ...  | B_i_+ |         ...
+         | B_i_- |
+          ------- 
+    
+    :param int N_c: number of unit cells to include in the cell
+    :param dict system_params: parameters
+    
+    :rtype kwant.system.FiniteSystem:
+    '''
+    
+    # make lattices and sublattices
+    lat = kwant.lattice.Polyatomic(prim_vecs = [[1,0],[0,1]], basis = [[1,0],[1,0], [0,-1],[0,-1], [0,1],[0,1]])
+    a_lat_pos, a_lat_neg, b_lat_pos, b_lat_neg, c_lat_pos, c_lat_neg = lat.sublattices
+    
+    #make builder and populate with onsite and hoppings
+    syst = kwant.Builder()
+    
+    
+    for i in range(N_c):
+        
+        #staggered point
+        sp = 2*i
+        
+        syst[a_lat_pos(sp,0)] = 0
+        syst[a_lat_neg(sp,0)] = 0
+        syst[b_lat_pos(sp,0)] = 0
+        syst[b_lat_neg(sp,0)] = 0
+        syst[c_lat_pos(sp,0)] = 0
+        syst[c_lat_neg(sp,0)] = 0
+        
+        if i < N_c - 1:
+        
+            
+            syst[c_lat_pos(sp+2,0)] = 0
+            syst[b_lat_pos(sp+2,0)] = 0
+            syst[c_lat_neg(sp+2,0)] = 0
+            syst[b_lat_neg(sp+2,0)] = 0
+
+            # + <--> + 
+            syst[a_lat_pos(sp,0), c_lat_pos(sp+2,0)] = 1
+            syst[a_lat_pos(sp,0), b_lat_pos(sp+2,0)] = 1
+
+            # - <--> -
+            syst[a_lat_neg(sp,0), c_lat_neg(sp+2,0)] = 1
+            syst[a_lat_neg(sp,0), b_lat_neg(sp+2,0)] = 1
+
+            # + <--> - 
+            syst[a_lat_pos(sp,0), b_lat_neg(sp+2,0)] = 1
+            syst[a_lat_neg(sp,0), b_lat_pos(sp+2,0)] = 1
+
+            # + <--> - hopping with phase
+            syst[a_lat_pos(sp,0), c_lat_neg(sp+2,0)] = 1
+            syst[a_lat_neg(sp,0), c_lat_pos(sp+2,0)] = 1
+            
+        # + <--> + 
+        syst[a_lat_pos(2*i,0), c_lat_pos(sp,0)] = 1
+        syst[a_lat_pos(2*i,0), b_lat_pos(sp,0)] = 1
+        # - <--> -
+        syst[a_lat_neg(2*i,0), c_lat_neg(sp,0)] = 1
+        syst[a_lat_neg(2*i,0), b_lat_neg(sp,0)] = 1
+        # + <--> - 
+        syst[a_lat_pos(2*i,0), c_lat_neg(sp,0)] = 1
+        syst[a_lat_neg(2*i,0), c_lat_pos(sp,0)] = 1
+        # + <--> - hopping with phase
+        syst[a_lat_pos(2*i,0), b_lat_neg(sp,0)] = 1
+        syst[a_lat_neg(2*i,0), b_lat_pos(sp,0)] = 1
+        
+    
+
+    
+    
+    return syst
+
+m = diamond_chain_system(10,None)
+
+kwant.plot(m)
+
+
+
+

code/testing_ground.py

+