NWChem User Documentation Release 5.0 Molecular Sciences Software Group W.R. Wiley Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory P.O. Box 999, Richland, WA 99352 September 2006 2 DISCLAIMER This material was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the United States Department of Energy, nor Battelle, nor any of their employees, MAKES ANY WARRANTY, EXPRESS OR IMPLIED, OR ASSUMES ANY LEGAL LIABILITY OR RESPON- SIBILITY FOR THE ACCURACY, COMPLETENESS, OR USEFULNESS OF ANY INFORMATION, APPARA- TUS, PRODUCT, SOFTWARE, OR PROCESS DISCLOSED, OR REPRESENTS THAT ITS USE WOULD NOT INFRINGE PRIVATELY OWNED RIGHTS. LIMITED USE This software (including any documentation) is being made available to you for your internal use only, solely for use in performance of work directly for the U.S. Federal Government or work under contracts with the U.S. Department of Energy or other U.S. Federal Government agencies. This software is a version which has not yet been evaluated and cleared for commercialization. Adherence to this notice may be necessary for the author, Battelle Memorial Institute, to successfully assert copyright in and commercialize this software. This software is not intended for duplication or distribution to third parties without the permission of the Manager of Software Products at Pacific Northwest National Laboratory, Richland, Washington, 99352. ACKNOWLEDGMENT This software and its documentation were produced with Government support under Contract Number DE-AC05- 76RL01830 awarded by the United States Department of Energy. The Government retains a paid-up non-exclusive, irrevocable worldwide license to reproduce, prepare derivative works, perform publicly and display publicly by or for the Government, including the right to distribute to other Government contractors. 3 4 AUTHOR DISCLAIMER This software contains proprietary information of the authors, Pacific Northwest National Laboratory (PNNL), and the US Department of Energy (USDOE). The information herein shall not be disclosed to others, and shall not be reproduced whole or in part, without written permission from PNNL or USDOE. The information contained in this document is provided “AS IS” without guarantee of accuracy. Use of this software is prohibited without written per- mission from PNNL or USDOE. The authors, PNNL, and USDOE make no representations or warranties whatsoever with respect to this software, including the implied warranty of merchant-ability or fitness for a particular purpose. The user assumes all risks, including consequential loss or damage, in respect to the use of the software. In addition, PNNL and the authors shall not be obligated to correct or maintain the program, or notify the user community of modifications or updates that will be made over the course of time. Contents 1 Introduction 19 1.1 Citation . 19 1.2 User Feedback . 20 2 Getting Started 23 2.1 Input File Structure . 23 2.2 Simple Input File — SCF geometry optimization . 24 2.3 Water Molecule Sample Input File . 25 2.4 Input Format and Syntax for Directives . 27 2.4.1 Input Format . 27 2.4.2 Format and syntax of directives . 28 3 NWChem Architecture 31 3.1 Database Structure . 31 3.2 Persistence of data and restart . 33 4 Functionality 35 4.1 Molecular electronic structure . 35 4.2 Relativistic effects . 37 4.3 Pseudopotential plane-wave electronic structure . 37 4.4 Molecular dynamics . 38 4.5 Python . 38 4.6 Parallel tools and libraries (ParSoft) . 39 5 Top-level directives 41 5.1 START and RESTART — Start-up mode . 41 5.2 SCRATCH_DIR and PERMANENT_DIR — File directories . 43 5 6 CONTENTS 5.3 MEMORY — Control of memory limits . 44 5.4 ECHO — Print input file . 45 5.5 TITLE — Specify job title . 46 5.6 PRINT and NOPRINT — Print control . 46 5.7 SET — Enter data in the RTDB . 47 5.8 UNSET — Delete data in the RTDB . 49 5.9 STOP — Terminate processing . 49 5.10 TASK — Perform a task . 49 5.10.1 TASK Directive for Electronic Structure Calculations . 50 5.10.2 TASK Directive for Special Operations . 51 5.10.3 TASK Directive for the Bourne Shell . 52 5.10.4 TASK Directive for QM/MM simulations . 53 5.11 CHARGE — Total system charge . 53 5.12 ECCE_PRINT — Print information for Ecce . 54 6 Geometries 57 6.1 Keywords on the GEOMETRY directive . 58 6.2 SYMMETRY — Symmetry Group Input . 60 6.3 Cartesian coordinate input . 61 6.4 ZMATRIX — Z-matrix input . 62 6.5 ZCOORD — Forcing internal coordinates . 68 6.6 Applying constraints in geometry optimizations . 69 6.7 SYSTEM — Lattice parameters for periodic systems . 69 7 Basis sets 71 7.1 Basis set library . 73 7.2 Explicit basis set definition . 74 7.3 Combinations of library and explicit basis set input . 75 8 Effective Core Potentials 77 8.1 Scalar ECPs . 78 8.2 Spin-orbit ECPs . 80 9 Relativistic All-electron Approximations 83 9.1 Douglas-Kroll approximation . 84 9.2 Dyall’s Modified Dirac Hamitonian approximation . 85 CONTENTS 7 10 Hartree-Fock or Self-consistent Field 89 10.1 Wavefunction type . 89 10.2 SYM — use of symmetry . 90 10.3 ADAPT – symmetry adaptation of MOs . 90 10.4 TOL2E — integral screening threshold . 91 10.5 VECTORS — input/output of MO vectors . 91 10.5.1 Superposition of fragment molecular orbitals . 94 10.5.2 Atomic guess orbitals with charged atoms . 99 10.6 Accuracy of initial guess . 100 10.7 THRESH — convergence threshold . 100 10.8 MAXITER — iteration limit . 100 10.9 PROFILE — performance profile . 101 10.10DIIS — DIIS convergence . 101 10.11DIRECT and SEMIDIRECT — recomputation of integrals . 101 10.11.1 Integral File Size and Format for the SCF Module . 103 10.12SCF Convergence Control Options . 104 10.13NR — controlling the Newton-Raphson . 105 10.14LEVEL — level-shifting the orbital Hessian . 105 10.15Orbital Localization . 106 10.16Printing Information from the SCF Module . 108 10.17Hartree-Fock or SCF, MCSCF and MP2 Gradients . 109 11 DFT for Molecules (DFT) 111 11.1 Specification of Basis Sets for the DFT Module . 113 11.2 VECTORS and MAX_OVL — KS-MO Vectors . 114 11.3 XC and DECOMP — Exchange-Correlation Potentials . 114 11.3.1 Exchange-Correlation Functionals . 115 11.3.2 Combined Exchange and Correlation Functionals . 116 11.3.3 Meta-GGA Functionals . 116 11.4 LB94 and CS00 — Asymptotic correction . 117 11.5 Sample input file . 117 11.6 ITERATIONS — Number of SCF iterations . ..