Tensor[ConformalKillingVectors] - calculate the conformal Killing vectors for a given metric
Calling Sequences
ConformalKillingVectors(g, options )
Parameters
g - a metric tensor on a manifold
options - any of the following keywords arguments: ansatz, unknowns, auxiliaryequations, coefficientvariables, parameters, output
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Description
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The program ConformalKillingVectors generates the defining system of 1st order PDE for a conformal vector field and uses pdsolve to find the solutions to these PDE.
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The command ConformalKillingVectors returns a sequence of two lists. The first list contains the non-trivial conformal Killing vectors and the second the Killing vectors. If there are no non-trivial conformal Killing vector fields then the first list is empty.
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When using the keyword argument ansatz, additional algebraic or differential conditions may be imposed upon the unknowns using the keyword argument auxiliaryequations Here is a list of the auxiliary equations to be added to the conformal Killing equations.
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This command is part of the DifferentialGeometry:-Tensor package, and so can be used in the form ConformalKillingVectors(...) only after executing the commands with(DifferentialGeometry), with(Tensor) in that order. It can always be used in the long form DifferentialGeometry:-Tensor:-ConformalKillingVectors(...).
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Examples
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Example 1.
We find the conformal Killing vectors for the Euclidean metric in 3 dimensions.
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| (2.2) |
There are a total of 10 conformal Killing vectors, 6 of which are Killing vectors.
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We can check this result by calculating the Lie derivative of the metric with respect to these vector fields (see LieDerivative) . We see that the vector fields are conformal Killing tensors and that the vector fields are Killing vectors.
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| (2.5) |
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We can use the LieAlgebraData command in the LieAlgebras package to calculate the structure equations for the Lie algebra of conformal Killing vectors.
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| (2.7) |
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This output shows, for example, that the Lie bracket of the first and third vector fields in is minus the first vector field.
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The Lie algebra of conformal Killing vector fields is a simple Lie algebra, that is, it is indecomposable and semi-simple.
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We check these properties using the Query command from the LieAlgebras package.
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CVF >
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Example 2.
We look for conformal Killing vector fields for the metric , of the special form specified by the vector .
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| (2.13) |
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Example 3.
We look for conformal Killing vector fields for the metric which have constant divergence. These are also known as homothetic vector fields.
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| (2.17) |
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Example 4.
We find the general conformal Killing vector for the metric depending upon 10 constants.
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| (2.19) |
Example 5.
We calculate the conformal Killing vector fields for the metric which depends upon 3 parameters , where . For generic values of the parameters there are no non-trivial conformal Killing vectors. However, there are non-trivial conformal Killing vectors in 3 exceptional cases :
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| (2.20) |
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Exceptional Case 1:
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| (2.22) |
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| (2.23) |
Exceptional Case 2:
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| (2.24) |
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Exceptional Case 3:
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| (2.26) |
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| (2.27) |
Generic Case.
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| (2.28) |
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| (2.29) |
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