I prefer using ALTER DATABASE ... MODIFY FILE to move database files. This method preserves the database ownership and does not require a detach/attach of the database.

The first step is to modify the file location:

ALTER DATABASE {your database} MODIFY FILE (filename = {new file location and name});

GO

Then, you take the database offline:

ALTER DATABASE {your database} SET OFFLINE WITH ROLLBACK IMMEDIATE;

GO

Once the database is offline, copy the file to the new location and name and then bring the database online:

ALTER DATABASE {your database} SET ONLINE;

GO