New Post: How to create top level/root site collection?

I've got a web app URL of https://intranet.mydomain.co.uk and I'm trying to create a root site collection so for the Managed PAth and URL i have set "/"

For the Site Collection and Site URL I have left these blank as effectively I just want a root site collection so the internal URL would be https://intranet.mydomain.co.uk/

However it now throws an error and when i try to enter "/" in the Site Collection and URL boxes after saving the xml file it wipes out the"/"

Any ideas?
Thanks :)

• Applying object cache accounts to "https://intranet.mydomain.co.uk:443"...
• Granting i:0#.w|ntservers\SPCACHESUPERUSER2013 Full Control to https://intranet.mydomain.co.uk/...
• Granting i:0#.w|ntservers\SPCACHEREAD2013 Full Read to https://intranet.mydomain.co.uk/...
• Done applying object cache accounts to "https://intranet.mydomain.co.uk:443"
• Checking for Site Collection ""...
• Creating new content database "SP_intranet"...

- Creating Site Collection ""...

• Script halted!
  

Exception : System.Management.Automation.ParameterBindingValidationException: Cannot bind argument to

                    parameter 'Url' because it is an empty string.
                       at System.Management.Automation.ExceptionHandlingOps.CheckActionPreference(FunctionContext
                    funcContext, Exception exception)
                       at System.Management.Automation.Interpreter.ActionCallInstruction`2.Run(InterpretedFrame
                    frame)
                       at
                    System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame
                    frame)
                       at
                    System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame
                    frame)