TBM3 (Tight-Binding Modeling for Materials at Mesoscale) is a C++ based numerical tool package and framework that designed for construct ‘any’ kind of lattice structure with multi-orbital and spin degree of freedom to solve the basic nano-scale electronic structure. It is to designed to construct a highly flexible and reusable framework for anyone to easily solve the multi-scale quantum mechnical model and extract useful physical quantities.
- A general lattice input file with orbital information specified.
- Providing non-spin polarized and spin polarized calculation with normal (non-superconductive), Nambu and extended Nambu space.
- Meanfield self-consistence and LLG spin dynamic calculations.
- Modeling for superconductivities in spin singlet and triplet states of any given symmetry.
- Simple and minimal input format for the setting of a quantum mechanical model.
- Simple file formate for the storage of order parameters.
First thing is to construct the lattice file. Here is an example for a single site Fe atom with two orbitals (dxz & dyz) for the iron based compound (BaFe2As2). Here we name the lattice input file as BaFe2As2.lat.
#BasisVector
1 0 0
0 1 0
0 0 1
#OrbitalProfile
Fe dxz dyz
#Atoms
1 0 0 0
Next, we can design and construct the tight-binding hopping term for the lattice. Here we choose the parameter sets from this paper Phys. Rev. B 88, 184509 (2013). Here we the model setting input file follows the lattice filename as BaFe2As2.lat.tbm.
#Parameters
isCalculateMu = 1
isCalculateVar = 0
isCalculateLDOS = 0
isCalculateBand = 1
spin = "on"
space = "normal"
bondRadius = 3
Mu = 0
Temperature = 0.0001
t1 = 0.09
t2 = 0.08
t3 = 1.35
t4 = -0.12
t5 = -1
t6 = 0.25
#CoreCharge
Fe > 2
#Hamiltonian
hoppingHc > Fe:Fe:+1+0+0 1:1 > t1
hoppingHc > Fe:Fe:+1+0+0 2:2 > t1
hoppingHc > Fe:Fe:+0+1+0 1:1 > t1
hoppingHc > Fe:Fe:+0+1+0 2:2 > t1
hoppingHc > Fe:Fe:+1+1+0 1:1 > t2
hoppingHc > Fe:Fe:+1-1+0 2:2 > t2
hoppingHc > Fe:Fe:+1+1+0 2:2 > t3
hoppingHc > Fe:Fe:+1-1+0 1:1 > t3
hoppingHc > Fe:Fe:+1+1+0 1:2 > t4
hoppingHc > Fe:Fe:+1-1+0 1:2 > t4
hoppingHc > Fe:Fe:-1-1+0 1:2 > t4
hoppingHc > Fe:Fe:-1+1+0 1:2 > t4
hoppingHc > Fe:Fe:+1+0+0 1:2 > t5
hoppingHc > Fe:Fe:+0+1+0 1:2 > t5
hoppingHc > Fe:Fe:-1+0+0 1:2 > t5
hoppingHc > Fe:Fe:+0-1+0 1:2 > t5
hoppingHc > Fe:Fe:+2+0+0 1:1 > t6
hoppingHc > Fe:Fe:+0+2+0 1:1 > t6
hoppingHc > Fe:Fe:+2+0+0 2:2 > t6
hoppingHc > Fe:Fe:+0+2+0 2:2 > t6
#KPointPath
G 0 0 0
X 1 0 0
M 1 1 0
G 0 0 0
In above, the keyword hopingHc describe a Hermitian conjugate hopping term from one Fe site to another (Fe:Fe:+1+0+0) for the specific (inter-)orbitals (1:1, 2:2, 1:2) with a given parameter (t1, t2, t3, t4, t5). The bond direction is described in the notation +1+0+0.
Afterwards, you can create another block to calculate the band structure along the given #KPointPath.
Now, we are good to execute the program under the terminal:
tbm-run BaFe2As2.lat
It will automatically calculate the chemical potential for the given electron charge (2 electrons per Fe site), and output the band structure 'BaFe2As2.lat.ban' under the same folder.
More examples can be found under the example/ folder.
- A NVIDIA GPU.
- CUDA library.
- MAGMA library.
- BOOST library.
We are working on to provide more possible options for different hardward selections.
Please see the installation guide in the "TBM3-document-1.0.pdf" under the doc folder.
TBM3 is licensed under the BSD Berkeley Software Distribution.
- Dr. Yuan-Yen Tai: Personal web, Linked In
- Dr. Jian-Xin Zhu: Personal web
- Compile options for Blabs for CPU, GPU-OpenCL and multi-thread-CPU.
- Charge/Spin susceptibility calculation.
- Transport calculation.
- Quantum MD simulation.
- Real space self-consistence for strongly correlated Hubbard interaction.