This leads to a new point on the surface, higher or lower in energy than the starting point. The step is taken if the new energy is lower. The Metropolis step is taken only if the expression is less than the random number. He modified the code to accept only downhill steps and increased the number searches for the next step. The old algorithm differs from the new as a Western pinball machine differs from a Japanese pachinko game.
Pinball sends out one ball.
But pachinko machines send out many balls that all fall in strictly descending paths. With enough balls, at least one is likely to fall in the highest payoff slot. The use of such algorithmic tradeoffs in investigating simple LJ clusters points to the possible validity of similarly mixed approaches to more complicated protein-folding problems, he noted. For 98 atoms, the code generates sequences of about 20 descending moves ending in a low-lying local minimum. As sequences progress, it's harder to find descending moves, so the process uses millions of local optimizations.