From owner-nwchem-users@emsl.pnl.gov Fri Jul 23 03:57:59 2004 Received: from odyssey.emsl.pnl.gov (localhost [127.0.0.1]) by odyssey.emsl.pnl.gov (8.12.10/8.12.10) with ESMTP id i6NAvxHQ023561 for ; Fri, 23 Jul 2004 03:57:59 -0700 (PDT) Received: (from majordom@localhost) by odyssey.emsl.pnl.gov (8.12.10/8.12.10/Submit) id i6NAvxZC023560 for nwchem-users-outgoing; Fri, 23 Jul 2004 03:57:59 -0700 (PDT) Date: Fri, 23 Jul 2004 12:57:47 +0200 (CEST) From: Giacomo Mulas Subject: optimisations with TDDFT... To: NWChem users mailing list Reply-to: Giacomo Mulas Message-id: MIME-version: 1.0 Content-type: TEXT/PLAIN; charset=US-ASCII X-OAC-capitanata-MailScanner: Found to be clean Sender: owner-nwchem-users@emsl.pnl.gov Precedence: bulk I am trying to optimise the geometry of an excited state of pyrene (C16H10) with the TDDFT module of NWChem 4.6. However the calculation seems to keep moving very close to the minimum without ever achieving convergence, i.e. @ Step Energy Delta E Gmax Grms Xrms Xmax Walltime @ ---- ---------------- -------- -------- -------- -------- -------- -------- @ 0 -614.91022048 0.0E+00 0.00010 0.00003 0.00000 0.00000 54151.0 @ 1 -614.91022088 -4.1E-07 0.00010 0.00003 0.00001 0.00002 110577.2 @ 2 -614.91022091 -2.5E-08 0.00004 0.00001 0.00000 0.00001 167769.1 @ 3 -614.91022136 -4.5E-07 0.00004 0.00001 0.00000 0.00001 223972.0 @ 4 -614.91022074 6.2E-07 0.00011 0.00003 0.00000 0.00000 280433.8 @ 5 -614.91022019 5.4E-07 0.00010 0.00003 0.00000 0.00001 337418.8 @ 6 -614.91022030 -1.0E-07 0.00009 0.00002 0.00003 0.00008 393508.2 @ 7 -614.91022027 2.5E-08 0.00008 0.00002 0.00005 0.00014 449935.4 @ 8 -614.91021986 4.1E-07 0.00014 0.00004 0.00034 0.00097 506341.5 @ 9 -614.91022070 -8.4E-07 0.00004 0.00001 0.00022 0.00063 562493.9 @ 10 -614.91022083 -1.3E-07 0.00006 0.00001 0.00021 0.00053 618855.6 @ 11 -614.91022035 4.8E-07 0.00012 0.00003 0.00000 0.00001 675141.7 @ 12 -614.91022036 -6.6E-09 0.00011 0.00003 0.00002 0.00006 731346.5 @ 13 -614.91022048 -1.2E-07 0.00004 0.00001 0.00007 0.00017 788165.0 @ 14 -614.91022037 1.1E-07 0.00007 0.00002 0.00006 0.00016 844614.2 @ 15 -614.91022041 -4.5E-08 0.00007 0.00002 0.00000 0.00000 900861.3 @ 16 -614.91022048 -6.3E-08 0.00007 0.00002 0.00000 0.00000 957467.0 @ 17 -614.91022041 6.2E-08 0.00007 0.00002 0.00000 0.00000 1013831.9 A couple of questions about optimising the geometry of excited states with TDDFT (maybe some of them might be useful in the FAQ or as caveats about TDDFT in the manual): 1) should the convergence criteria be relaxed for TDDFT instead of using the defaults? 2) should the assumed accuracy of the energy be lowered with the ?? directive instead of using the defaults? 3) should a smaller step be used when calculating numeric gradients? If you are already very close to the minimum but the energy hypersurface is strongly anharmonic, numerically calculated gradients might appear to be nonzero just because finite differences are calculated between points too far from the minimum. 4) any other suggestion/caveat about trying to optimise the geometry of excited states with the TDDFT module of NWChem 4.6? Thanks, bye Giacomo -- _________________________________________________________________ Giacomo Mulas _________________________________________________________________ OSSERVATORIO ASTRONOMICO DI CAGLIARI Str. 54, Loc. Poggio dei Pini * 09012 Capoterra (CA) Tel. (OAC): +39 070 71180 248 Fax : +39 070 71180 222 Tel. (UNICA): +39 070 675 4916 _________________________________________________________________ "When the storms are raging around you, stay right where you are" (Freddy Mercury) _________________________________________________________________