You can create a magnetic vector potential boundary condition to prescribe magnetic vector potential on a surface. (For more information, see “Boundary conditions” in “Eddy current analysis,” Section 6.7.5 of the Abaqus Analysis User's Guide.) The magnetic vector potential boundary condition is available only in an electromagnetic model.
To specify a magnetic vector potential:
Display the magnetic vector potential boundary condition editor using one of the following methods:
To create a new magnetic vector potential boundary condition, follow the procedure outlined in “Creating boundary conditions,” Section 16.8.2 (Category: Electrical/Magnetic; Types for Selected Step: Magnetic vector potential).
To edit an existing magnetic vector potential boundary condition using menus or managers, see “Editing step-dependent objects,” Section 3.4.13. To edit the region to which the boundary condition is applied, see “Editing the region to which a prescribed condition is applied,” Section 16.8.4.
Click the arrow to the right of the Distribution field, and select the option of your choice from the list that appears:
Select Uniform to define a boundary condition that is uniform over the surface.
Select User-defined to define the magnitude and direction of the boundary condition in user subroutine UDEMPOTENTIAL. See the following sections for more information:
If you selected the Uniform distribution option, perform the following steps:
In the Component 1, Component 2, and (if applicable) Component 3 fields, enter the real (in-phase) and imaginary (out-of-phase) parts of the magnetic vector potential.
Abaqus/CAE calculates the magnitude and direction of the magnetic vector potential.
If desired, click the arrow to the right of the Amplitude field, and select the amplitude of your choice from the list that appears. Alternatively, you can click 
to create a new amplitude. (See Chapter 57, “The Amplitude toolset,” for more information.)
Click OK to save your data and to exit the editor.
If you selected the User-defined distribution option, perform the following steps:
If desired, in the Component 1, Component 2, and (if applicable) Component 3 fields enter the real (in-phase) and imaginary (out-of-phase) parts of the magnetic vector potential.
Abaqus/CAE calculates the magnitude and direction of the magnetic vector potential and that information is passed into the user subroutine.
Click OK to save your data and to exit the editor.
Enter the Job module and display the job editor for the analysis job of interest. (For more information, see “Creating, editing, and manipulating jobs,” Section 19.7.)
In the job editor, click the General tab, and specify the file containing the user subroutine that defines the magnitude and direction of the boundary condition. For more information, see “Specifying general job settings,” Section 19.8.6.
Note: You can specify only one user subroutine file in the job editor; if your analysis involves more than one user subroutine, you must combine the user subroutines into one file and then specify that file.
