$FRAGNAME

$FRAGNAME group (required for each FRAGNAME given in $EFRAG)

This group gives all pertinent information for a given effective fragment potential (EFP). This information falls into three categories:

electrostatic (distributed multipoles, screening)
distributed polarizabilities
exchange repulsion

It is input using several different subgroups, which should be given in the order shown below. Each subgroup is specified by a particular name, and is terminated by the word STOP. You may omit any of the subgroups to omit that term from the EFP. All values are given in atomic units.

To input monopoles, follow input sequence -EM-
To input dipoles, follow input sequence -ED-
To input quadrupoles, follow input sequence -EQ-
To input octupoles, follow input sequence -EO-
To input screening parameters, follow input sequence -ES-
To input polarizable points, follow input sequence -P-
To input repulsive points, follow input sequence -R-

-1- a single descriptive title card


-2- COORDINATES

COORDINATES signals the start of the subgroup containing the multipolar expansion terms (charges, dipoles, ...). Optionally, one can also give the coordinates of the polarizable points, or centers of exchange repulsion.

-3- NAME, X, Y, Z, WEIGHT, ZNUC

NAME is a unique string identifying the point. X, Y, Z are the Cartesian coordinates of the point. WEIGHT and ZNUC are the atomic mass and nuclear charge, and are given only for the points which are nuclei.

Typically the true nuclei will appear twice, once for defining the positive nuclear charge and its screening, and a second time for defining the electronic distributed multipoles.

Repeat line -3- for each expansion point, and terminate the list with a "STOP".


-EM1- MONOPOLES

MONOPOLES signals the start of the subgroup containing the electronic and nuclear monopoles.

-EM2- NAME, CHARGE

NAME must match one given in the COORDINATES subgroup. CHARGE = nuclear or electronic monopole at this point.

Repeat -EM2- to define all desired charges. Terminate this subgroup with a "STOP".


-ED1- DIPOLES

DIPOLES signals the start of the subgroup containing the dipolar part of the multipolar expansion.

-ED2- NAME, MUX, MUY, MUZ

NAME must match one given in the COORDINATES subgroup. MUX, MUY, MUZ are the components of the electronic dipole.

Repeat -ED2- to define all desired dipoles. Terminate this subgroup with a "STOP".


-EQ1- QUADRUPOLES

QUADRUPOLES signals the start of the subgroup containing the quadrupolar part of the multipolar expansion.

-EQ2- NAME, XX, YY, ZZ, XY, XZ, YZ

NAME must match one given in the COORDINATES subgroup. XX, YY, ZZ, XY, XZ, and YZ are the components of the electronic quadrupole moment.

Repeat -EQ2- to define all desired quadrupoles. Terminate this subgroup with a "STOP".


-EO1- OCTUPOLES

OCTUPOLES signals the start of the subgroup containing the octupolar part of the multipolar expansion.

-EO2- NAME, XXX, YYY, ZZZ, XXY, XXZ, XYY, YYZ, XZZ, YZZ, XYZ

NAME must match one given in the COORDINATES subgroup. XXX, ... are the components of the electronic octupole.

Repeat -EO2- to define all desired octupoles. Terminate this subgroup with a "STOP".


-ES1- SCREENSCREEN signals the start of the subgroup containing the screening terms (A*exp[-B*r**2]) for the distributed multipoles, which account for charge penetration effects.

-ES2- NAME, A, B

NAME must match one given in the COORDINATES subgroup. A, B are the parameters of the Gaussian screening term.

Repeat -ES2- to define all desired screening points. Terminate this subgroup with a "STOP".


-P1- POLARIZABLE POINTS

POLARIZABLE POINTS signals the start of the subgroup containing the distributed polarizability tensors, and their coordinates.

-P2- NAME, X, Y, Z

NAME gives a unique identifier to the location of this polarizability tensor. It might match one of the points already defined in the COORDINATES subgroup, but often does not. Typically the distributed polarizability tensors are located at the centroids of localized MOs.

X, Y, Z are the coordinates of the polarizability point. They should be omitted if NAME did appear in COORDINATES. The units are controlled by UNITS= in $CONTRL.

-P3- XX, YY, ZZ, XY, XZ, YZ, YX, ZX, ZY

XX, ... are components of the distributed polarizability, which is not a symmetric tensor. XY means dMUx/dFy, where MUx is a dipole component, and Fy is a component of an applied field.

Repeat -P2- and -P3- to define all desired polarizability tensors, and terminate this subgroup with a "STOP".


-R1- REPULSIVE POTENTIAL

REPULSIVE POTENTIAL signals the start of the subgroup containing the fitted exchange repulsion potential, for the interaction between the fragment and the ab initio part of the system. This term also accounts for charge transfer effects. The term has the form

         
                 N
                sum   C * exp[-D  * r**2]
                 i     i        i
  

-R2- NAME, X, Y, Z, N

NAME may match one given in the COORDINATES subgroup, but need not. If NAME does not match one of the known points, you must give its coordinates X, Y, and Z, otherwise omit these three values. N is the total number of terms in the fitted repulsive potential.

-R3- C, D

These three values define the i-th term in the repulsive potential. Repeat line -R3- for all N terms.

Repeat -R2- and -R3- to define all desired repulsive potentials, and terminate this subgroup with a "STOP".


The entire $FRAGNAME group is terminated by a " $END".


Back to list of input groups...