DEHam/README.md

DEHam

Double Exchange Hamiltonian: Complete Version

(under GNU GENERAL PUBLIC LICENSE v2)

Dependencies

1. PETSc and SLEPc

2. IRPF90

Compiling

1. Export environment variables for PETSc and SLEPc

export PETSC_DIR=${PATH_TO_PETSC_INSTALLATION}
export SLEPC_DIR=${PATH_TO_SLEPC_INSTALLATION}
export C_INCLUDE_PATH+=:$PETSC_DIR/include/:$SLEPC_DIR/include:$PETSC_DIR/arch-linux2-c-debug/include/:$SLEPC_DIR/arch-linux2-c-debug/include
# The "arch-linux2-c-debug" directory can have different names depending on PETSC and SLEPC installation procedure.

2. Make the executable

make ex1

Using DEHam

1. The DEHam program requires an input file which has the topology of the Hamiltonian and the various parameters as explained below in a sample inputfile:

140   # The total number of determinants (Ndet)
7     # The number of orbitals (total)
1     # The largest number of non-zero elements per row (Multiple of Ndet)
2     # The total number of processors used in parallel (Multiple of Ndet)
1     # The number of holes
0     # The isz (ms-1/2) value
true     # Restrict the hole to the 1'st (i.e. half of natom) Family of states. *false* for no restrictions
1,2,3,1,2,3,4,5,6,7 # The topology of the system is specified here
2,3,4,8,7,6,5,6,7,8 # first and second line contain the two sites linked
1,1,1,2,2,2,2,3,3,3 # third line contains the type of link (1 for t, J 2 for K and 3 for none)
.1430,-0.20,0.0000  # The three types of links this line gives J, K
.1430,-0.20,0.0000  # 
-1.00,0.0,0.00      # This line gives t

2. running DEHam

mpiexec -n [nprocs] ./ex1 inpfile 

Publications using this code

1. High-Spin Chains and Crowns from Double-Exchange Mechanism doi:10.3390/cryst6040039