Would you tell me how to use Hamiltonian Monte Carlo sampling method in Beast?

[Lixian Su]

Hello, I tried to use the Hamiltonian Monte Carlo sampling method (HMC) in Beast. Because I cannot select the HMC model directly, therefore, I have to edit the .XML file which is generated by Beauti. I just change the code of the operator of the .XML file, however, I met with a fatal error and I have no idea how to figure it out. Would you help me with how to address this problem? And is there any other method to use the HMC in Beast? If there is a better way to utilize the HMC model, would you tell me?

The error is shown in the pic.

This is the code that I have changed.