Get only parent post in archive post

I created custom post type using cpt plugin and trying to create custom template to my new post type.
I want to display only parent posts
and then display child posts in parent post page, but when trying to get only parent post nothing appears
my code :

$args = array(
                  'post_type' => 'programs',
                        'post_parent' => get_the_ID(),
                    );
                    $article_posts = new WP_Query($args);

                    if($article_posts->have_posts()) : 
                    ?> 
                            <?php while($article_posts->have_posts()) : $article_posts->the_post(); 
                            $post_id = get_the_ID();
                            $post_link = get_permalink($post_id);
                            $post_title = get_the_title();