Write a json file for the phononwebsite:
        http://henriquemiranda.github.io/phononwebsite

def write_phononwebsite(self,filename):
        """
        Write a json file for the phononwebsite:
        http://henriquemiranda.github.io/phononwebsite
        """
        import json
        with open(filename,'w') as f:
            phononwebsite_json = json.dump(self.as_phononwebsite(),f)