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documentation:language_reference:functions:calculateg [2024/11/14 14:47] – Aleksandrs Zacinskisdocumentation:language_reference:functions:calculateg [2025/11/20 03:29] (current) – external edit 127.0.0.1
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 ### ###
-Function //CalculateG(HTB, Options)// calculates single-particle Green's function from a given Tight-Binding Object //HTB//, which can be created using the function //[[documentation:language_reference:functions:NewTightBinding|NewTightBinding()]]//.+Function //CalculateG(HTB, Options)// calculates single-particle Green's function from a given Tight-Binding Object //HTB//.
 ### ###
  
 ===== Input ===== ===== Input =====
  
-  * //HTB// : Tight-binding object+  * //HTB// : Tight-binding object, which can be created using the function //[[documentation:language_reference:functions:NewTightBinding|NewTightBinding()]]//
   * Options : A table of options. Possible options are:   * Options : A table of options. Possible options are:
       * //"Emin"// : Real, minimum value of the energy. Default value is -10       * //"Emin"// : Real, minimum value of the energy. Default value is -10
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 ===== Output ===== ===== Output =====
  
-  * G : Response Function object of the form $\{\{A_0, a_1, a_2,\dots,a_n\},\{ B_1,B_2, \dots, B_n \}, $ type="ListOfPoles" $\dots \}$ +  * G : Response Function in the Block List of Poles (If not chosen otherwise) representation $\{\{A_0, a_1, a_2,\dots,a_n\},\{ B_1,B_2, \dots, B_n \}, $ type="ListOfPoles" $\dots \}$, which corresponds to  
 +$$G(\omega) = A_0 + \sum_{k} \frac{B_k}{\omega-a_k+i\gamma/2}$$ 
 +where $a_1,\dots,a_n$ are real numbers, and $A_0,B_1,\dots, B_n$ are matrices of dimensions $N_O \times N_O $, where $N_O$ is the number of orbitals in //HTB.Atoms//.
 ===== Example ===== ===== Example =====
  
 ### ###
-description text+This example creates Tight-Binding model for 2D layer of CuO2 also known as the Emery model. //CalculateG()// Is used to calculate and plot Green's functions. Code in the example relies on the user-written function //ScalarResponseFunctionFromBlockListOfPolesResponseFunction()// that is given at the end of the page.
 ### ###
  
 ==== Input ==== ==== Input ====
 <code Quanty Example.Quanty> <code Quanty Example.Quanty>
--- some example code+-- define on-site energies and hopping parameters 
 +ed = -1 
 +ep1 = -3 
 +ep2 = ep1  
 +t = 1 -- tdp 
 +tdd = 0.1 
 +tpp = 0.3 
 +HTB = NewTightBinding() 
 +HTB.Name = "Emery model" 
 + 
 +HTB.Cell = {{1,0,0},{0,1,0},{0,0,1}} 
 + 
 +HTB.Atoms = {{"Cu",{0.5,0.5,0},{{"d",{"x^2y^2"}}}}, 
 +             {"O1",{1,0.5,0},{{"p",{"x"}}}}, 
 +             {"O2",{0.5,1,0},{{"p",{"y"}}}}} 
 + 
 +HTB.Hopping = { {"Cu.d","Cu.d",{0,0,0},{{ed}}}, 
 +                {"O1.p","O1.p",{0,0,0},{{ep1}}}, 
 +                {"O2.p","O2.p",{0,0,0},{{ep2}}}, 
 +                {"Cu.d","O1.p",{0.5,0,0},{{t}}}, 
 +                {"Cu.d","O1.p",{-0.5,0,0},{{t}}}, 
 +                {"O1.p","Cu.d",{0.5,0,0},{{t}}}, 
 +                {"O1.p","Cu.d",{-0.5,0,0},{{t}}}, 
 +                {"Cu.d","O2.p",{0,0.5,0},{{t}}}, 
 +                {"Cu.d","O2.p",{0,-0.5,0},{{t}}}, 
 +                {"O2.p","Cu.d",{0,0.5,0},{{t}}}, 
 +                {"O2.p","Cu.d",{0,-0.5,0},{{t}}}, 
 +                {"Cu.d","Cu.d",{1,0,0},{{tdd}}}, 
 +                {"Cu.d","Cu.d",{0,1,0},{{tdd}}}, 
 +                {"Cu.d","Cu.d",{-1,0,0},{{tdd}}}, 
 +                {"Cu.d","Cu.d",{0,-1,0},{{tdd}}}, 
 +                {"O1.p","O2.p",{0.5,0.5,0},{{tpp}}}, 
 +                {"O1.p","O2.p",{0.5,-0.5,0},{{tpp}}}, 
 +                {"O1.p","O2.p",{-0.5,0.5,0},{{tpp}}}, 
 +                {"O1.p","O2.p",{-0.5,-0.5,0},{{tpp}}}, 
 +                {"O2.p","O1.p",{0.5,0.5,0},{{tpp}}}, 
 +                {"O2.p","O1.p",{0.5,-0.5,0},{{tpp}}}, 
 +                {"O2.p","O1.p",{-0.5,0.5,0},{{tpp}}}, 
 +                {"O2.p","O1.p",{-0.5,-0.5,0},{{tpp}}} 
 +            } 
 +-- Calculate Block Greens Function 
 +G0Block= CalculateG(HTB,{{"NE",1e4},{"Nk",{1000,1000,1}}}) 
 +-- Extract single orbital Green's functions for plotting 
 +G0_Cu = ScalarResponseFunctionFromBlockListOfPolesResponseFunction(G0Block,1,1) 
 +G0_O1 = ScalarResponseFunctionFromBlockListOfPolesResponseFunction(G0Block,2,2) 
 +G0_O2 = ScalarResponseFunctionFromBlockListOfPolesResponseFunction(G0Block,3,3) 
 +G0_Cu_O1 = ScalarResponseFunctionFromBlockListOfPolesResponseFunction(G0Block,1,2) 
 +G0_Cu_O2 = ScalarResponseFunctionFromBlockListOfPolesResponseFunction(G0Block,1,3) 
 +G0_O1_O2 = ScalarResponseFunctionFromBlockListOfPolesResponseFunction(G0Block,2,3) 
 +G0_O2_O1 = ScalarResponseFunctionFromBlockListOfPolesResponseFunction(G0Block,3,2) 
 +G0_O1_Cu =  ScalarResponseFunctionFromBlockListOfPolesResponseFunction(G0Block,2,1) 
 +G0_O2_Cu =  ScalarResponseFunctionFromBlockListOfPolesResponseFunction(G0Block,3,1) 
 +-- Plot Green's functions (Density of States) 
 +Emin=-12 
 +Emax=7 
 +Ymin=-4 
 +Ymax=3 
 + 
 +Pl  = Graphics.Plot({G0_Cu,G0_Cu_O1,G0_Cu_O2,G0_O1_Cu,G0_O1,G0_O1_O2,G0_O2_Cu,G0_O2_O1,G0_O2,["GammaG"]=0.1}, {{"Nrow",3},{"NColumn",3},{"Frame",{{"Ymin",Ymin},{"Ymax",Ymax},{"Xmin",Emin},{"Xmax",Emax},{"dYTick",1},{"dXTick",2},{"FontSize",0.03},{"YFormat","%3.1f"},{"XLabel","E [t]"},{"YLabel","G"}}}}) 
 +PlSVG = Graphics.ToSVG(Pl) 
 +file,err = io.open("DOS_ij.svg",'w') 
 +file:write(PlSVG) 
 +file:close() 
 </code> </code>
  
 ==== Result ==== ==== Result ====
-<file Quanty_Output> +Diagonal Elements of the plots below show Partial DOS of Cu,O1,O2.  
-text produced as output +{{ :documentation:language_reference:functions:pes_ij.png?800 |}}
-</file>+
  
 +
 +==== Used functions ====
 +<code Quanty function.Quanty>
 +-- this function extracts G_ij response function of Block List of Poles Response Function object
 +function ScalarResponseFunctionFromBlockListOfPolesResponseFunction(G0,i,j)
 +    local G0T = ResponseFunction.ToTable(G0)
 +    local k
 +    local A0_ij = G0T[1][1][i][j] 
 +    local ai = G0T[1] 
 +    table.remove(ai,1) --remove matrix A0
 +    table.insert(ai,1,A0_ij) -- add number A0_ij
 +    local bw_ij = {}
 +    for k=1,#G0T[2] do  -- from k=1 to NE
 +        bw_ij[#bw_ij+1] = G0T[2][k][i][j]
 +    end
 +    G_ij = ResponseFunction.New( {ai,bw_ij,mu=0,type="ListOfPoles", name="G0"} )
 +    return G_ij
 +end
 +</code>
 ===== Table of contents ===== ===== Table of contents =====
 {{indexmenu>.#1}} {{indexmenu>.#1}}
  

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