<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Dear Limin,<div><br class="webkit-block-placeholder"></div><div>Please read carefully the error/warning messages:</div><div><br class="webkit-block-placeholder"></div><div><div><div>On 10 Mar 2008, at 01:36, lmliu wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; ">*** 01:34:59 WARNING in force_env_methods:mixed_energy_forces err=-300 ***<br> *** ASSERTION (cond) failed at line 1151 Error (0.129985E-11) in ***<br> *** computing numerical derivatives larger then(0.100000E-11) . ***</span></blockquote></div></div><div><br></div><div>First: this is not an error message but it is a warning (WARNING in [..]). </div><div>Second: It clearly says that: Error (0.129985E-11) in computing numerical derivatives larger then(0.100000E-11) .</div><div><br class="webkit-block-placeholder"></div><div>I guess you can cope with this error on the evaluation of the MIXED forces.. don't you (look at the magnitude of the numbers)?</div><div>If you are annoyed from seeing this warning message you can tune the precision of the evaluation of the numerical derivative</div><div>with the keyword:</div><div><br class="webkit-block-placeholder"></div><div><a href="http://cp2k.berlios.de/input/InputReference~__ROOT__~FORCE_EVAL~MIXED~GENERIC.html#ERROR_LIMIT">http://cp2k.berlios.de/input/InputReference~__ROOT__~FORCE_EVAL~MIXED~GENERIC.html#ERROR_LIMIT</a></div><div><br class="webkit-block-placeholder"></div><div>10^-12 is an extremely safe parameter. I guess 10^-7 will do your work in a very good way as well (please compare these numbers</div><div>with the precision achieved in computing the DFT forces).</div><div>Cheers,</div><div>Teo</div><div><br class="webkit-block-placeholder"></div></body></html>