BoxVolumeCV.h

#pragma once 

#include "CollectiveVariable.h"
#include "Validator/ObjectRequirement.h"
#include "Drivers/DriverException.h"
#include "Snapshot.h"
#include "schema.h"

namespace SSAGES
{

    class BoxVolumeCV : public CollectiveVariable
    {
    public:
        BoxVolumeCV()
        {}

        void Initialize(const Snapshot& snapshot) override
        {
        }


        void Evaluate(const Snapshot& snapshot) override
        {
            // Fill empty gradient. 
            auto n = snapshot.GetNumAtoms();
            std::fill(grad_.begin(), grad_.end(), Vector3{0,0,0});
            grad_.resize(n, Vector3{0,0,0});

            val_ = snapshot.GetVolume();
            if(snapshot.GetCommunicator().rank() == 0)
                boxgrad_ = val_*Matrix3::Identity();
        }
        
        static BoxVolumeCV* Build(const Json::Value& json, const std::string& path)
        {
            Json::ObjectRequirement validator;
            Json::Value schema;
            Json::Reader reader;

            reader.parse(JsonSchema::BoxVolumeCV, schema);
            validator.Parse(schema, path);

            // Validate inputs.
            validator.Validate(json, path);
            if(validator.HasErrors())
                throw BuildException(validator.GetErrors());

            return new BoxVolumeCV();
        }
    };
}