minimize lbfgs <minimize-lbfgs-statement> end
<minimize-lbfgs-statement> :==
tolgradient=<real>
Tolerence for early termination of minimization. If the norm
of the gradient of the total energy falls below this value
minimization will stop. Default=0.0001
The limited-memory BFGS method of Liu and Nocedal is used. This
uses a quasi-Newton minimization method. For further details see:
D. C. Liu and J. Nocedal, On the limited memory BFGS method for
large-scale optimization, Math. Programming 45, (1989) 503-528.