Qt: Problems with QPSQL driver not loaded

This is my code for the main.ccp :

#include <QCoreApplication>
#include<QtSql>
#include<QtDebug>
#include<Iostream>
#include <QSqlDatabase>
#include <QSqlError>
#include <QSqlQuery>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QSqlDatabase db = QSqlDatabase::addDatabase("QPSQL");
     db.setHostName("localhost");
     db.setDatabaseName("bd_gdv");
     db.setUserName("postgres");
     db.setPassword("xxxxxxxx");

    if (db.open())
    {
     qDebug() <<"DB Opened";
     db.close();
     }
    else
    {
      qDebug() << db.lastError().text();
     }
    return a.exec();
}

This code gives me the following error, I have searched for information but it is not clear to me how it is that the drivers are loaded

  

QSqlDatabase: QPSQL driver not loaded

     

QSqlDatabase: available drivers: QSQLITE QMYSQL QMYSQL3 QODBC QODBC3 QPSQL QPSQL7 "Driver not loaded Driver not loaded"