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Quick Start |
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There is a test program written to demonstrate the abilities of the
expansion package. This program called test-expansion allows
you to calculate some basic expansions.
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Syntax definition of the input file |
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[ Series expansions |
Excitations |
Utilities ]
In the following the syntax of the input file of the test-expansion
program is defined. The program is run with two arguments defining
the name of the input and output file. If not specified, the default
names are input and output.
| Series expansions |
| Syntax of expression |
Semantics of expression |
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GroundStateExpansion n clusterfile energyfile
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Evaluates a ground state expansion of order n. The underlying
clusters are read from the referenced cluster file.
The coefficients of the energy perturbation series per cluster
is saved in the referenced energy file. This data is needed for
the evaluation of effective hamiltonians.
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EffectiveHamiltonian n clusterfile energyfile
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Evaluates the effective hamiltonian as an expansion of order n.
The underlying clusters are read from the referenced cluster file.
The ground state energy perturbation series is read from the
referenced energy file as described above.
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| Excitations |
| Syntax of expression |
Semantics of expression |
| ParticleExcitation |
Switches the actual excitation to a particle excitation.
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| HoleExcitation |
Switches the actual excitation to a hole excitation.
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| Utilities |
| Syntax of expression |
Semantics of expression |
| ClassifyGroundStateClusters filename |
Evaluates for every cluster in the given file the order
it contributes first in a ground state expansion.
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| // some comment |
Allows you to add some comments to your input file. Notice that
comments are only allowed at the end of an expression statement,
but not in between.
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| Exit |
Exit the program.
Everything beyond this statement won't be interpreted.
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Fat printed expressions are terminal symbols not to be
changed. Normal printed expressions have to be specified in the
input file by the user. Expression enclosed in <> - brackets are
optional.
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Examples |
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For an easy use some examples are given in the following.
Example 1: Bose Hubbard model on the 1D linear chain
GroundStateExpansion 12 lRaw6.txt lRaw6.mott
ParticleExcitation
EffectiveHamiltonian 12 lRaw6.txt lRaw6.mott
Exit
Example 2: Bose Hubbard model on the 2D quadratic lattice
GroundStateExpansion 8 qRaw8.txt qRaw8.mott
Exit
Example 3
ClassifyGroundStateClusters qRaw8.txt
Exit
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