Given the function $f ( x ) = a x - \frac { 1 } { x } - ( a + 1 ) \ln x$ . (1) When $a = 0$ , find the maximum value of $f ( x )$ ; (2) If $f ( x )$ has exactly one zero point, find the range of values for $a$ .
Given the function $f ( x ) = a x - \frac { 1 } { x } - ( a + 1 ) \ln x$ .
(1) When $a = 0$ , find the maximum value of $f ( x )$ ;
(2) If $f ( x )$ has exactly one zero point, find the range of values for $a$ .