This is not good, because the skin under the chin looks heavy. Instead, extend your neck slightly when smiling. This will define the jaw line and make the face look lighter. If you are not smiling and want a neutral expression keep your lips slightly parted. This will define the shape of your mouth neutrally, otherwise you could look severe without intending to.
Most people have many barriers or walls they erect around themselves.
To get a good picture you need to let go. Rip down the walls and let the photographer see who you are. Show the real you. A good photographer will work toward this goal, but it really helps if you do the same. If you are very nervous in front of the camera this won't happen.