Hello everyone: I am a newbie in Quantum Chemistry and I want to do some calculation on some physical properties such as the title shows. However, as we know, lots of package can't give you exactly what you want,you have to tackle with some succeeding process to get a beatiful result which may be used in your paper. There is the question: how can I get non-linear optical coefficient from results of calculation by, for example, GAUSSIAN? And is there anyone who is familiar with it and may give me some help? More thanks.