[CPMD-list] Discrepancy between MORTENSEN and TUCKERMAN

[Salomon Billeter]

Dear Eung-Gun,

is there also a difference between single-point energies (same geometry,
same or random initial wavefunction)? What system do you calculate? I
cannot reproduce such a large difference (i.e., I get the same numbers for
both Poisson solvers for your settings with ethylene up to 10^-5 atomic
units and very parallel evolution of the optimization). It's possible that
you are converging to two slightly separated local minima. Did you make
sure there is enough empty space in each direction?
Just a hint for easier convergence: If you are using quite a tough
convergence criterion such as 10^-6 AU and have a healthy system, I'd
strongly recommend using CONVERGENCE ADAPT (e.g. 0.02) and (if not
restarting from a good wavefunction) CONVERGENCE INITIAL (e.g. 0.02 times
the gradient on ions you expect for the first step).
Could you please tell us more about your system?

Best regards,
Salomon