Is it permissible for a father to give charity from his wealth to his poor married children, and is it permissible for him to give them his zakat?

Voluntary charity (Sadaqat al-Tatawwu') to poor relatives is desirable, even if they are among those whom one is obligated to support. It is better than giving charity to strangers. As for Zakat, it is not permissible to give it to parents or children whom the giver is obligated to support, because that would relieve him of an obligation and the benefit would return to him. An exception to this is if the giver is unable to support them; in this case, it is permissible to give them Zakat.