Concat two different fields in cakephp in find statement

<?php
$this->ModelName->virtualFields = array(
    'full_name' => "CONCAT(ModelName.first_name, ' ', ModelName.last_name)"
);
$list = $this->ModelName->find("all", array(
    "fields" => array(
        "ModelName.id",
        "ModelName.full_name"
    )
));
?>