We wish to perform an SCF calculation at the geometry r(C-H)=1.099 A, r(C-O)=1.203 A and angle HCO=121.8o. The geometry is specified through use of the z-matrix [2,3], where each line of the ZMATRIX directive is responsible for specifying the nature and location of a given nucleus in terms of the position of those nuclei defined by previous lines. Note at the outset that the z-matrix TAGs used to characterise the component nuclei of the system play a vital role in characterising the system. They act, for example, to define the charge of the component nuclei and are used in establishing the effective point group symmetry of the system. The program incorporates a number of `built-in' basis sets, with the split-valence 3-21G basis due to Pople et al  as the default. The following data sequence would be required in performing the SCF calculation using this default basis:
TITLE H2CO - 3-21G DEFAULT BASIS - CLOSED SHELL SCF ZMATRIX ANGSTROM C O 1 1.203 H 1 1.099 2 121.8 H 1 1.099 2 121.8 3 180.0 END ENTERNote that this data sequence assumes a number of default specifications; the corresponding sequence specifying these defaults in-line would be as follows;
(*) DUMPFILE ED3 1 (*) MAINFILE ED2 (*) MINBLOCK ED2 1 (*) MAXBLOCK ED2 99999 (*) ADAPT ON TITLE H2CO - FULL DATA SPECIFICATION (*) CHARGE 0 (*) MULT 1 (*) SUPER ON ZMATRIX ANGSTROM C O 1 1.203 H 1 1.099 2 121.8 H 1 1.099 2 121.8 3 180.0 END (*) BASIS SV 3-21G (*) RUNTYPE SCF (*) SCFTYPE RHF (*) LEVEL 1.0 5 0.3 (*) DIIS ON (*) VECTORS ATOMS (*) ENTER 1
where the default specifications which apply in the present closed-shell single point geometry calculation are indicated by a (*). In particular
In default efficiency considerations are used in deciding the appropriate format based on the particular computation to be undertaken (as defined by the SCFTYPE directive). Considerable Caution must be exercised when considering usage of the Mainfile produced in one phase of the computation in some subsequent phase, and specification of the SUPER directive provides some control over this usage. The default and available integral options are summarised in Table 2, where the specified defaults are those appropriate to RUNTYPE SCF.
|Open-shell RHF||J+K||J+K,2-electron integral|
|MP2||2-electron integral||2-electron integral|
|MP3||2-electron integral||2-electron integral|
|CASSCF||2-electron integral||2-electron integral|
|MCSCF||2-electron integral||2-electron integral|
Thus, for example, attempting to use the integral file produced in default during a closed-shell SCF calculation (P-supermatrix) in a subsequent open-shell computation must be considered an invalid operation, and will lead to an error condition.
|RUNTYPE INTEGRAL||Single point integral calculation|
|RUNTYPE SCF||Single point integral plus SCF calculation|
|RUNTYPE OPTIMIZE||Geometry optimisation (internal coordinates)|
|RUNTYPE OPTXYZ||Geometry optimisation (cartesian coordinates)|
|RUNTYPE SADDLE||Saddle point location|
|RUNTYPE FORCE||Force constant evaluation|
|RUNTYPE HESSIAN||Analytic Force constant evaluation|
|RUNTYPE POLARISABILITY||Polarisability calculation|
|RUNTYPE HYPER||Hyperpolarisability calculation|
|RUNTYPE MAGNET||Magnetisability calculation|
|RUNTYPE RAMAN||Calculation of Raman Intensities|
|RUNTYPE INFRARED||Calculation of IR intensities|
|RUNTYPE ANALYSE||Wavefunction analysis|
|RUNTYPE TRANSFORM||Integral transformation|
|RUNTYPE CI||CI calculation|
|RUNTYPE GF||Green's Function OVGF calculation|
|RUNTYPE TDA||Green's Function 2ph-TDA calculation|
|RUNTYPE RESPONSE||Response calculations of Excitation Energies|
|SCFTYPE RHF||Restricted Hartree-Fock|
|SCFTYPE UHF||Unrestricted Hartree-Fock|
|SCFTYPE DIRECT UHF||Direct-UHF|
|SCFTYPE GVB||Generalised Valence Bond|
|SCFTYPE DIRECT GVB||Direct-GVB|
|SCFTYPE MP2||2nd order Møller Plesset|
|SCFTYPE MP3||3nd order Møller Plesset|
|SCFTYPE CASSCF||Complete Active Space SCF|
|SCFTYPE MCSCF||2nd order MCSCF|
Note that additional directives may be required in further characterising the SCFTYPE specification. The default program options are
RUNTYPE SCF SCFTYPE RHFi.e. single point restricted Hartree-Fock SCF computation.
TITLE H2CO - MINIMAL STO3G BASIS - CLOSED SHELL SCF ZMATRIX ANGSTROM C O 1 1.203 H 1 1.099 2 121.8 H 1 1.099 2 121.8 3 180.0 END BASIS STO3G ENTERThe corresponding data for performing an extended, triple-zeta plus polarisation (TZVP) basis is shown below.
TITLE H2CO - EXTENDED TZVP BASIS - CLOSED SHELL SCF ZMATRIX ANGSTROM C O 1 1.203 H 1 1.099 2 121.8 H 1 1.099 2 121.8 3 180.0 END BASIS TZVP ENTER
The default Cartesian angular functions (6 d, 10 f, 15 g) used throughout GAMESS-UK may now be overridden under control of the HARMONIC directive. This provides the option of using spherical-harmonic (5 d, 7 f, 9g) angular functions. Note that such usage is implemented internally through appropriate transformations, and not by computing integrals or derivative integrals over the spherical functions.
Typical usage will involve just presenting the string HARMONIC. Thus the data for performing an extended, triple-zeta plus polarisation (TZVP) spherical harmonic basis is shown below.
TITLE H2CO - EXTENDED TZVP SPHERICAL HARMONIC BASIS - CLOSED SHELL SCF HARMONIC ZMATRIX ANGSTROM C O 1 1.203 H 1 1.099 2 121.8 H 1 1.099 2 121.8 3 180.0 END BASIS TZVP ENTERThe following points should be noted: