1% 2% $Id$ 3% 4\label{sec:property} 5 6Properties can be calculated for both the Hartree-Fock and DFT wave 7functions. The properties that are available are: 8 9\begin{itemize} 10\item Natural bond analysis 11\item Dipole, quadrupole, and octupole moment 12\item Mulliken population analysis and bond order analysis 13\item Electrostatic potential (diamagnetic shielding) at nuclei 14\item Electric field and field gradient at nuclei 15\item Electron and spin density at nuclei 16\item NMR shielding (GIAO method) 17\item NMR hyperfine coupling (Fermi-Contact and Spin-Dipole expectation values) 18\item NMR indirect spin-spin coupling 19\end{itemize} 20 21The properties module is started when the task directive 22\verb+TASK <theory> property+ is defined in the user input file. The input 23format has the form: 24 25\begin{verbatim} 26 PROPERTY 27 [property keyword] 28 [CENTER ((com || coc || origin || arb <real x y z>) default coc)] 29 END 30\end{verbatim} 31 32Most of the properties can be computed for Hartree-Fock 33(closed-shell RHF, open-shell ROHF, and open-shell UHF), and DFT 34(closed-shell and open-shell spin unrestricted) wavefunctions. The NMR 35chemical shift is limited to closed-shell wave functions, whereas the NMR 36hyperfine and indirect spin-spin coupling require a UHF or ODFT wave function. 37 38\section{Property keywords} 39 40Each property can be requested by defining one of the following keywords: 41 42\begin{verbatim} 43 NBOFILE 44 DIPOLE 45 QUADRUPOLE 46 OCTUPOLE 47 MULLIKEN 48 ESP 49 EFIELD 50 EFIELDGRAD 51 ELECTRONDENSITY 52 HYPERFINE 53 SHIELDING [<integer> number_of_atoms <integer> atom_list] 54 SPINSPIN [<integer> number_of_pairs <integer> pair_list] 55 AIMFILE 56 ALL 57\end{verbatim} 58 59The ``{\tt ALL}'' keyword generates all currently available properties. 60 61Both the NMR shielding and spin-spin coupling have additional optional 62parameters that can be defined in the input. For the shielding the user 63can define the number of atoms for which the shielding tensor should be 64calculated, followed by the list of specific atom centers. In the case 65of spin-spin coupling the number of atom pairs, followed by the atom 66pairs, can be defined (i.e., spinspin 1 1 2 will calculate the coupling 67for one pair, and the coupling will be between atoms 1 and 2). 68 69For both the NMR spin-spin and hyperfine coupling the isotope that has 70the highest abundance and has spin, will be choosen for each atom under 71consideration. 72 73The user also has the option to choose the center of expansion for 74the dipole, quadrupole, and octupole calculations. 75 76\begin{verbatim} 77 [CENTER ((com || coc || origin || arb <real x y z>) default coc)] 78\end{verbatim} 79 80\verb+com+ is the center of mass, \verb+coc+ is the center of charge, \verb+origin+ is 81(0.0, 0.0, 0.0) and \verb+arb+ is any arbitrary point which must be accompanied 82by the coordinated to be used. Currently the x, y, and z coordinates 83must be given in the same units as \verb+UNITS+ in \verb+GEOMETRY+ (See Section 84\ref{sec:geomkeys}). 85 86\subsection{Nbofile} 87\label{sec:Nbofile} 88 89The keyword {\tt NBOFILE} does not execute the Natural Bond Analysis 90code, but simply creates an input file to be used as input to the 91stand-alone NBO code. All other properties are calculated upon 92request. 93 94Following the successful completion of an electronic structure 95calculation, a Natural Bond Orbital (NBO) analysis may be carried out 96by providing the keyword \verb+NBOFILE+ in the \verb+PROPERTY+ directive. 97NWChem will query the rtdb and construct an ASCII file, 98\verb+<file_prefix>.gen+, that may be used as input to the stand alone 99version of the NBO program, gennbo. \verb+<file_prefix>+ is equal to 100string following the \verb+START+ directive. The input deck may be edited 101to provide additional options to the NBO calculation, (see the NBO 102user's manual for details.) 103 104\subsection{AIM file} 105\label{sec:AIMfile} 106 107The keyword {\tt aimfile} creates a \verb+.wfn+ file from a given 108eigenvector file (i.e., \verb+.movecs+), geometry and a basis set. 109The \verb+.wfn+ file summarizes the single determinant wavefunction in order to be analyzed 110through a third-party software. 111Among some known analyses are the Bader's approach for atoms in molecules (AIM), the electron 112localization function (ELF), the Fermi hole function and energy density analysis. 113The follow input directive will create the an AIM file \verb+.wfx+ format. 114\begin{verbatim} 115 set prop:nowfx F 116\end{verbatim} 117