From owner-nwchem-users@emsl.pnl.gov Thu Dec 8 12:19:52 2005 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 jB8KJqR8023885 for ; Thu, 8 Dec 2005 12:19:52 -0800 (PST) Received: (from majordom@localhost) by odyssey.emsl.pnl.gov (8.12.10/8.12.10/Submit) id jB8KJq0i023884 for nwchem-users-outgoing-0915; Thu, 8 Dec 2005 12:19:52 -0800 (PST) Date: Thu, 08 Dec 2005 12:19:46 -0800 From: "Bylaska, Eric J" Subject: RE: [NWCHEM] higher HOMO energy than LUMO To: Ali Sebetci Cc: nwchem-users@emsl.pnl.gov Message-id: MIME-version: 1.0 X-MIMEOLE: Produced By Microsoft Exchange V6.5.7226.0 Content-type: text/plain; charset=us-ascii Thread-Topic: [NWCHEM] higher HOMO energy than LUMO thread-index: AcX758DtfvLvTeNLQV6woDSUZSY0lgASm9mg Content-class: urn:content-classes:message X-MS-Has-Attach: X-MS-TNEF-Correlator: X-OriginalArrivalTime: 08 Dec 2005 20:19:50.0441 (UTC) FILETIME=[BDE64190:01C5FC34] Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by odyssey.emsl.pnl.gov id jB8KJpR8023881 Sender: owner-nwchem-users@emsl.pnl.gov Precedence: bulk Ali, What kind of functional are you using? Having a HOMO with higher energy than the LUMO may in fact be the lowest energy state in a DFT calculation because of self-interaction in DFT functional. For instance if you calculate the C2 dimer (in the singlet Sigma^+_g state) using a restricted LDA functional, the ground state solution has a LUMO with a lower energy than the HOMO. Eric -----Original Message----- From: owner-nwchem-developers@emsl.pnl.gov [mailto:owner-nwchem-developers@emsl.pnl.gov] On Behalf Of Ali Sebetci Sent: Thursday, December 08, 2005 2:51 AM To: nwchem-users@emsl.pnl.gov Subject: [NWCHEM] higher HOMO energy than LUMO Dear NWChem users, Sometimes, after optimization and frequency calculations in DFT model, I am ended up with a higher HOMO energy than the LUMO energy. For instance the following output: Vector 35 Occ=2.000000D+00 E=-1.960371D-01 MO Center= -1.8D-05, 3.5D-05, 3.6D-07, r^2= 4.3D+00 Bfn. Coefficient Atom+Function Bfn. Coefficient Atom+Function ----- ------------ --------------- ----- ------------ --------------- 38 0.606863 2 Pt dxy 86 -0.606830 4 Pt dxy 64 0.478231 3 Pt dyy 16 -0.478204 1 Pt dyy 13 0.441050 1 Pt dxx 61 -0.440974 3 Pt dxx 44 0.197941 2 Pt dxy 92 -0.197928 4 Pt dxy 70 0.152698 3 Pt dyy 22 -0.152694 1 Pt dyy Vector 36 Occ=2.000000D+00 E=-1.921981D-01 MO Center= 2.5D-05, -3.7D-05, 1.3D-07, r^2= 4.4D+00 Bfn. Coefficient Atom+Function Bfn. Coefficient Atom+Function ----- ------------ --------------- ----- ------------ --------------- 14 0.873936 1 Pt dxy 62 0.873923 3 Pt dxy 86 -0.693920 4 Pt dxy 38 -0.693890 2 Pt dxy 20 0.284152 1 Pt dxy 68 0.284129 3 Pt dxy 92 -0.261685 4 Pt dxy 44 -0.261675 2 Pt dxy Vector 37 Occ=0.000000D+00 E=-1.984438D-01 MO Center= -7.8D-05, 4.1D-06, -6.4D-07, r^2= 4.2D+00 Bfn. Coefficient Atom+Function Bfn. Coefficient Atom+Function ----- ------------ --------------- ----- ------------ --------------- 39 -0.828288 2 Pt dxz 87 0.828284 4 Pt dxz 17 -0.809661 1 Pt dyz 65 0.809542 3 Pt dyz 45 -0.208741 2 Pt dxz 93 0.208740 4 Pt dxz 23 -0.203196 1 Pt dyz 71 0.203168 3 Pt dyz Vector 36 (HOMO) energy (-0.193) is greater than the vector 37 (LUMO) energy (-0.198). Why does the program prefer to put the electrons in a higher energy orbital? Is there an option in NWChem to stabilize the wave function as in the case of Gaussian? How can I correct this? When I restart the single point calculation by swapping the vectors 37 and 36, I get the following result: Vector 35 Occ=2.000000D+00 E=-1.791164D-01 MO Center= -6.2D-04, -5.2D-04, 7.6D-05, r^2= 4.6D+00 Bfn. Coefficient Atom+Function Bfn. Coefficient Atom+Function ----- ------------ --------------- ----- ------------ --------------- 90 0.493474 4 Pt dzz 42 0.493283 2 Pt dzz 18 -0.388581 1 Pt dzz 66 -0.388183 3 Pt dzz 85 -0.277350 4 Pt dxx 37 -0.277262 2 Pt dxx 16 0.250045 1 Pt dyy 64 0.249749 3 Pt dyy 88 -0.193798 4 Pt dyy 40 -0.193713 2 Pt dyy Vector 36 Occ=2.000000D+00 E=-1.767279D-01 MO Center= -6.3D-04, -2.3D-04, 1.2D-04, r^2= 4.3D+00 Bfn. Coefficient Atom+Function Bfn. Coefficient Atom+Function ----- ------------ --------------- ----- ------------ --------------- 87 -0.859526 4 Pt dxz 39 0.859365 2 Pt dxz 17 0.765946 1 Pt dyz 65 -0.765109 3 Pt dyz 93 -0.235096 4 Pt dxz 45 0.235050 2 Pt dxz 23 0.202455 1 Pt dyz 71 -0.202218 3 Pt dyz Vector 37 Occ=0.000000D+00 E=-1.983823D-01 MO Center= 3.4D-04, 4.9D-05, -1.1D-04, r^2= 4.5D+00 Bfn. Coefficient Atom+Function Bfn. Coefficient Atom+Function ----- ------------ --------------- ----- ------------ --------------- 62 -0.846929 3 Pt dxy 14 -0.846644 1 Pt dxy 38 0.732718 2 Pt dxy 86 0.732668 4 Pt dxy 44 0.266760 2 Pt dxy 68 -0.266759 3 Pt dxy 92 0.266747 4 Pt dxy 20 -0.266711 1 Pt dxy Thanks in advance. Ali.