trigger a process model using script task

No. What do you try to achieve? Any reason to not use the "Start Process" smart service?

You can do it with Start process smart service, as [mention:a11f77a729fb4db2af76b09948583328:e9ed411860ed4f2ba0265705b8793d05] said... or you can create an integration that calls a web Api (and the web api executes a!startprocess, and call the integration from the script task...

Hi [mention:190a358f01ba46ab8c569b6353a5f5fa:e9ed411860ed4f2ba0265705b8793d05] ,

a!startprocess() is a function that can ne executed inside saveinto on an interface component or webApi.

As you want to start new process from process model, you can use subprocess or startprocess nodes. Or create an API and call that API inside an integration and use that integration in script task

Is there any specific reason behind using the startProcess function instead of the smart service?