$DATA group (required)
This group describes the global molecular data such as point group symmetry, nuclear coordinates, and possibly the basis set. It consists of a series of free format card images.
GROUP is the Schoenflies symbol of the symmetry group, you may choose from
C1, CS, CI, CN, S2N, CNH, CNV, DN, DNH, DND, T, TH, TD, O, OH.NAXIS is the order of the highest rotation axis, and must be given when the name of the group contains an N. For example, "CNV 2" is C2v.
For linear molecules, choose either CNV or DNH, and enter NAXIS as 4.
In order to use GAMESS effectively, you must be able to recognize the point group name for your molecule. This presupposes a knowledge of group theory at about the level of Cotton's "Group Theory", Chapter 3.
Armed with only the name of the group, GAMESS is able to exploit the molecular symmetry throughout almost all of the program, and thus save a great deal of computer time. GAMESS does not require that you know very much else about group theory, although a deeper knowledge (character tables, irreducible representations, term symbols, and so on) is useful when dealing with the more sophisticated wavefunctions.
Cards -3- and -4- are quite complicated, and are rarely given. A SINGLE blank card may replace both cards -3- and -4-, to select the 'master frame', which is defined on the next page. If you choose to enter a blank card, skip to the bottom of the next page.
Note! If the point group is C1 (no symmetry), skip over cards -3- and -4- (which means no blank card).
third point, and a directional parameter.
For CS group, one point of the symmetry plane, noncollinear with points 1 and 2.
For CI group, there is no card -4-.
For other groups, a generator sigma-v plane (if any) is the (x,z) plane of the local frame (CNV point groups).
A generator sigma-h plane (if any) is the (x,y) plane of the local frame (CNH and dihedral groups).
A generator C2 axis (if any) is the x-axis of the local frame (dihedral groups).
The perpendicular to the principal axis passing through the third point defines a direction called D1. If DIRECT='PARALLEL', the x-axis of the local frame coincides with the direction D1. If DIRECT='NORMAL', the x-axis of the local frame is the common perpendicular to D1 and the principal axis, passing through the intersection point of these two lines. Thus D1 coincides in this case with the negative y axis.
The 'master frame' is just a standard orientation for the molecule. By default, the 'master frame' assumes that
Use the lowest number rule that applies to your molecule.
Some examples of these rules:
In general, it is a poor idea to try to reorient the molecule. Certain sections of the program, such as the orbital symmetry assignment, do not know how to deal with cases where the 'master frame' has been changed.
Linear molecules (C4v or D4h) must lie along the z axis, so do not try to reorient linear molecules.
You can use EXETYP=CHECK to quickly find what atoms are generated, and in what order. This is typically necessary in order to use the general $ZMAT coordinates.
Depending on your choice for COORD in $CONTROL,
Card sequence U is the only one which allows you to define a completely general basis here in $DATA.
Recall that UNIT in $CONTRL determines the distance units.
Only the symmetry unique atoms are input, GAMESS will generate the symmetry equivalent atoms according to the point group selected above.
NAME,ZNUC,CONX,R,ALPHA,BETA,SIGN,POINT1,POINT2,POINT3
ref- R.L. Hilderbrandt, J.Chem.Phys. 51, 1654 (1969). You cannot understand HINT input without reading this.
Note that if ZNUC is negative, the internally stored basis for ABS(ZNUC) is placed on this center, but the calculation uses ZNUC=0 after this. This is useful for basis set superposition error (BSSE) calculations.
If you gave $BASIS, continue entering cards -5U- until all the unique atoms have been specified. When you are done, enter a " $END " card.
If you did not, enter cards -6U-, -7U-, -8U-.
GBASIS has exactly the same meaning as in $BASIS. You may choose from MINI, MIDI, STO, N21, N31, N311, DZV, DH, BC, TZV, MC, SBK, or HW. In addition, you may choose S, P, D, F, G, or L to enter an explicit basis set. Here, L means an s and p shell with a common exponent.
NGAUSS is the number of Gaussians (N) in the Pople style basis, or user input general basis. It has meaning only for GBASIS=STO, N21, N31, or N311, and S,P,D,F,G, or L.
Up to four scale factors may be entered. If omitted, standard values are used. They are not documented as every GBASIS treats these differently. Read the source code if you need to know more. They are seldom given.
If GBASIS is not S,P,D,F,G, or L, either add more shells by repeating card -6U-, or go on to -8U-.
If GBASIS=S,P,D,F,G, or L, enter NGAUSS cards -7U-.
For more shells on this atom, go back to card -6U-.
If there are no more shells, go on to card -8U-.
Continue entering atoms with -5U- through -8U- until all are given, then terminate the group with a " $END " card.
--- this is the end of card sequence U ---
Cartesian coordinates for all atoms must be entered. They may be arbitrarily rotated or translated, but must possess the actual point group symmetry. GAMESS will reorient the molecule into the 'master frame', and determine which atoms are the unique ones. Thus, the final order of the atoms may be different from what you enter here.
Continue entering atoms with card -5C- until all are given, and then terminate the group with a " $END " card.
--- this is the end of card sequence C ---
Only the name of the first atom is required. See -8G- for a description of this information.
Only a name and a bond distance is required for atom 2. See -8G- for a description of this information.
Only a name, distance, and angle are required for atom 3. See -8G- for a description of this information.
STRING is a symbolic string used in the Z-matrix.
VALUE is the numeric value to substitute for that string.
Continue entering -10G- until all STRINGs are defined. Note that any blank card encountered while reading -10G- will be ignored. GAMESS regards all STRINGs as variables (constraints are sometimes applied in $STATPT). It is not necessary to place constraints to preserve point group symmetry, as GAMESS will never lower the symmetry from that given at -2-. When you have given all STRINGs a VALUE, terminate the group with a " $END " card.
--- this is the end of card sequence G ---
Both Z-matrix input styles must generate a molecule which possesses the symmetry you requested at -2-. If not, your job will be terminated automatically.
Only the name of the first atom is required. See -8M- for a description of this information.
Only a name and a bond distance is required for atom 2. See -8M- for a description of this information.
Only a bond distance from atom 2, and an angle with repect to atom 1 is required for atom 3. If you prefer to hook atom 3 to atom 1, you must give connectivity as in -8M-. See -8M- for a description of this information.
ATOM, BLENGTH, ALPHA, BETA, i1, i2 and i3 are as described at -8G-. However, BLENGTH, ALPHA, and BETA must be given as numerical values only. In addition, BETA is always a dihedral angle. i1, i2, i3 must be integers only.
The j1, j2 and j3 integers, used in MOPAC to signal optimization of parameters, must be supplied but are ignored here. You may give them as 0, for example.
Continue entering atoms 3, 4, 5, ... with -8M- cards until all are given, and then terminate the group by giving a " $END " card.
--- this is the end of card sequence M ---
This is the end of $DATA!
If you have any doubt about what molecule and basis set you are defining, or what order the atoms will be generated in, simply execute an EXETYP=CHECK job to find out!