   |
AMPAC 8 User Manual |
| |
AMPAC 8 User Manual |
The ESP program module calculates the expectation values of the electrostatic potential of a molecule on a uniform distribution of points. The resultant ESP surface is then fit to atom centered charges that best reproduce the electron distribution in a least-squares sense. It offers the capability to accurately compute charges in situations where other methods may fail. The keyword ESP is required for all electrostatic potential calculations.
The set of points defining the default surface is generated according to the algorithm of Connolly.[21] Williams' method[22] for generating surfaces may be used as an alternative to the default Connolly procedure. Van der Waals radii for the Williams method are included for hydrogen, boron, carbon, nitrogen, oxygen, fluorine, phosphorous, sulfur, chlorine, bromine, and iodine. Van der Waals radii for all elements through chlorine plus zinc are included for the Connolly surfaces. For more information about the surface generation routines in AMPAC™, see the CONNOLLY and WILLIAMS keyword reference pages.
ESP integrals are equivalent to nuclear attraction integrals. The formulae of Obara and Saika[23] are used in the ESP subroutines. The great majority of the computation time for a semiempirical ESP calculation is taken in the integral calculation. At the end of the job, the surface points and electrostatic potential values may be written to file in plain text format if POTWRT is specified. This output is written to file jobname.esp using unit 20. The restarting of ESP jobs is no longer supported in AMPAC 8.
In general, the accuracy of an ESP charge calculation can be enhanced by increasing the number of probe points used for fitting on the Williams or Connolly surfaces. The number of probe points may be adjusted away from default values (determined to be generally adequate by experience) by utilizing the ESP dedicated keywords DEN and NSURF.
| CONNOLLY | Enable use of the Connolly surface for the ESP calculation. |
| DEN | Specify a different point density for the Connolly surface. |
| DIPOLE | Constrain the ESP dipole moment as predicted by AMPAC's Coulson analysis. |
| DIPX | Specify the x- component of the dipole moment. |
| DIPY | Specify the y- component of the dipole moment. |
| DIPZ | Specify the z- component of the dipole moment. |
| NSURF | Change the number of surfaces used in the Connolly algorithm. |
| POTWRT | Dump out the surface points and electrostatic potential values. |
| SCALE | Change the base scaling factor in the Connolly treatment. |
| SCINCR | Specify the increment between multipliers for the Connolly surface. |
| SLOPE | Change the scaling factor when using MNDO charges. |
| STO3G | Specify basis set to "deorthogonalize" the semiempirical density matrix. |
| STO6G | Specify basis set to "deorthogonalize" the semiempirical density matrix. |
| SYMAVG | Average charges which should have the same value by symmetry. |
| WILLIAMS | Specify surface generation procedure of Donald Williams. |
The implementation of ESP in AMPAC has been generalized to handle UHF and/or CI wavefunctions as well as the more regular RHF solutions. ESP will now also handle charged species. Also, rather than setting the maximum number of probe points available for fitting the surface as a constant (MESP), this value is computed dynamically at compile time based on the number of atoms according to the following equation:
where MAXAOP is the maximum number of atoms with p-orbitals allowed in the calculation.
Methanol using the MNDO model is computed with several ESP options on the common keyword line.
mndo rhf singlet esp t=auto truste symavg sto6g Methanol ESP STO6G H 0.000000 0 0.000000 0 0.000000 0 0 0 0 C 1.094000 1 0.000000 0 0.000000 0 1 0 0 O 1.425000 1 107.000000 1 0.000000 0 2 1 0 H 0.945000 1 108.500000 1 180.000000 1 3 2 1 H 1.094000 1 107.000000 1 -60.000000 1 2 3 4 H 1.094000 1 107.000000 1 60.000000 1 2 3 4 0 0.000000 0 0.000000 0 0.000000 0 0 0 0
Timestamp: 2004-02-12-14-44-59-0000007245-hpux
SUMMARY OF MNDO CALCULATION
Feb-12-2004
AMPAC Version 8.13
Presented by:
Semichem, Inc.
PO Box 1649
Shawnee KS 66222
(913)268-3271
(913)268-3445 (fax)
FORMULA: C1H4O1
Methanol
ESP STO6G
GEOMETRY OPTIMISED : ENERGY MINIMISED
SCF FIELD WAS ACHIEVED
FINAL HEAT OF FORMATION = -57.354087 kcal
= -240.026855 kJ
ELECTRONIC ENERGY = -1079.569548 eV
CORE-CORE REPULSION = 572.058004 eV
TOTAL ENERGY = -507.511543 eV
GRADIENT NORM = 0.105459
RMS GRADIENT NORM = 0.030443
UNSTABLE MODE(S) = 0 ( ESTIMATE )
DIPOLE = 1.479080 debyes
NO. OF FILLED LEVELS = 7 (OCC = 2)
KOOPMAN IONISATION POTENTIAL = 11.42 eV
MOLECULAR POINT GROUP = CS 0.100000
MOLECULAR WEIGHT = 32.042
COMPUTATION TIME = 0.03 seconds
FINAL GEOMETRY OBTAINED CHARGE
MNDO RHF SINGLET ESP T=AUTO TRUSTE SYMAVG STO6G
Methanol
ESP STO6G
H 0.000000 0 0.000000 0 0.000000 0 0 0 0 0.0161 
C 1.114964 1 0.000000 0 0.000000 0 1 0 0 0.1928
O 1.390658 1 108.078001 1 0.000000 0 2 1 0 -0.3291
H 0.946542 1 111.587140 1 180.000000 1 3 2 1 0.1803
H 1.119107 1 112.312290 1 -60.585897 1 2 3 4 -0.0300
H 1.119107 1 112.312290 1 60.585897 1 2 3 4 -0.0300
0 0.000000 0 0.000000 0 0.000000 0 0 0 0
Timestamp: 2004-02-12-14-44-59-0000007245-hpux
*******************************************************************************
MNDO CALCULATION RESULTS
*******************************************************************************
* AMPAC Version 8.13
* Presented by:
*
* Semichem, Inc.
* PO Box 1649
* Shawnee KS 66222
* (913)268-3271
* (913)268-3445 (fax)
*
* TRUSTE - MINIMISE ENERGY USING TRUST REGION
* ESP - ELECTROSTATIC POTENTIAL CALCULATION
* SYMAVG - AVERAGE SYMMETRY EQUIVALENT ESP CHARGES
* T=AUTO - AUTOMATIC DETERMINATION OF ALLOWED TIME
* SINGLET - IS THE REQUIRED SPIN MULTIPLICITY
*******************************************************************************
MNDO RHF SINGLET ESP T=AUTO TRUSTE SYMAVG STO6G
Methanol
ESP STO6G
ATOM CHEMICAL BOND LENGTH BOND ANGLE TWIST ANGLE
NUMBER SYMBOL (ANGSTROMS) (DEGREES) (DEGREES)
(I) NA:I NB:NA:I NC:NB:NA:I NA NB NC
1 H
2 C 1.09400 * 1
3 O 1.42500 * 107.00000 * 2 1
4 H 0.94500 * 108.50000 * 180.00000 * 3 2 1
5 H 1.09400 * 107.00000 * -60.00000 * 2 3 4
6 H 1.09400 * 107.00000 * 60.00000 * 2 3 4
MOLECULAR POINT GROUP SYMMETRY CRITERIA
CS 0.10000000
SINGLET STATE CALCULATION
** REFERENCES TO PARAMETERS **
H (MNDO): M.J.S. DEWAR, W. THIEL, J. AM. CHEM. SOC., 99, 4899, (1977)
C (MNDO): M.J.S. DEWAR, W. THIEL, J. AM. CHEM. SOC., 99, 4899, (1977)
O (MNDO): M.J.S. DEWAR, W. THIEL, J. AM. CHEM. SOC., 99, 4899, (1977)
-------------------------
* External Contributors *
-------------------------
Electrostatic Potential Charge Calculation:
-------------------------------------------
The ESP charge method was contributed by Brent B. Besler (Wayne State
University) and Kenneth D. Merz (Penn State University).
CARTESIAN COORDINATES
NO. ATOM X Y Z
1 1 0.0000 0.0000 0.0000
2 6 1.0940 0.0000 0.0000
3 8 1.5106 1.3627 0.0000
4 1 2.4553 1.3875 0.0000
5 1 1.5007 -0.4588 -0.9060
6 1 1.5007 -0.4588 0.9060
STANDARD DEVIATION ON ENERGY (KCAL) 0.00000055520
STANDARD DEVIATION ON GRADIENT (KCAL/A,RD,RD) 0.00009841 0.00010918 0.00009144
MNDO RHF SINGLET ESP T=AUTO TRUSTE SYMAVG STO6G
Methanol
ESP STO6G
GEOMETRY OPTIMISED : ENERGY MINIMISED
SCF FIELD WAS ACHIEVED
MNDO CALCULATION
VERSION 8.13
Feb-12-2004
FINAL HEAT OF FORMATION = -57.354087 kcal
= -240.026855 kJ
ELECTRONIC ENERGY = -1079.569548 eV
CORE-CORE REPULSION = 572.058004 eV
TOTAL ENERGY = -507.511543 eV
GRADIENT NORM = 0.105459
RMS GRADIENT NORM = 0.030443
UNSTABLE MODE(S) = 0 ( ESTIMATE )
IONISATION POTENTIAL = 11.415002 eV
MOLECULAR POINT GROUP = CS 0.100000
NO. OF FILLED LEVELS = 7 (OCC = 2)
MOLECULAR WEIGHT = 32.042
SCF CALCULATIONS = 7
COMPUTATION TIME = 0.03 seconds
ATOM CHEMICAL BOND LENGTH BOND ANGLE TWIST ANGLE
NUMBER SYMBOL (ANGSTROMS) (DEGREES) (DEGREES)
(I) NA:I NB:NA:I NC:NB:NA:I NA NB NC
1 H
2 C 1.11496 * 1
3 O 1.39066 * 108.07800 * 2 1
4 H 0.94654 * 111.58714 * 180.00000 * 3 2 1
5 H 1.11911 * 112.31229 * -60.58590 * 2 3 4
6 H 1.11911 * 112.31229 * 60.58590 * 2 3 4
MOLECULAR POINT GROUP SYMMETRY CRITERIA
CS 0.10000000
RHF EIGENVALUES
-41.93366 -27.81197 -18.66532 -15.39933 -15.31487 -12.81818 -11.41500 3.78981
3.93566 4.69959 5.00626 6.75555
NET ATOMIC CHARGES AND DIPOLE CONTRIBUTIONS
ATOM NO. TYPE CHARGE ATOM ELECTRON DENSITY
1 H 0.0161 0.9839
2 C 0.1928 3.8072
3 O -0.3291 6.3291
4 H 0.1803 0.8197
5 H -0.0300 1.0300
6 H -0.0300 1.0300
DIPOLE (DEBYE) X Y Z TOTAL
POINT-CHG. 0.322 -0.732 -0.000 0.800
HYBRID 0.631 -0.399 -0.000 0.746
SUM 0.953 -1.131 -0.000 1.479
CARTESIAN COORDINATES
NO. ATOM X Y Z
1 H 0.0000 0.0000 0.0000
2 C 1.1150 0.0000 0.0000
3 O 1.5465 1.3220 0.0000
4 H 2.4913 1.3799 -0.0000
5 H 1.4665 -0.5617 -0.9019
6 H 1.4665 -0.5617 0.9019
ATOMIC ORBITAL ELECTRON POPULATIONS
0.98392 1.22135 0.91613 0.78148 0.88826 1.81752 1.23477 1.31288
1.96394 0.81966 1.03004 1.03004
NAICAS 16.67 PERCENT IN 0.01 SECONDS 
NAICAS 33.33 PERCENT IN 0.03 SECONDS
NAICAS 50.00 PERCENT IN 0.04 SECONDS
NAICAS 66.67 PERCENT IN 0.06 SECONDS
NAICAS 83.33 PERCENT IN 0.07 SECONDS
NAICAS 100.00 PERCENT IN 0.07 SECONDS
NAICAP 20.00 PERCENT IN 0.01 SECONDS
NAICAP 40.00 PERCENT IN 0.01 SECONDS
NAICAP 60.00 PERCENT IN 0.02 SECONDS
NAICAP 80.00 PERCENT IN 0.02 SECONDS
NAICAP 100.00 PERCENT IN 0.02 SECONDS
ELECTROSTATIC POTENTIAL CHARGES
CHARGE ON SYSTEM = 0.0000
ATOM NO. TYPE CHARGE SCALED CHARGE 
1 H 0.0257 0.0365
2 C 0.2079 0.2956
3 O -0.4818 -0.6851
4 H 0.3048 0.4335
5 H -0.0282 -0.0400
6 H -0.0285 -0.0405
THE NUMBER OF POINTS IS: 427 
THE RMS DEVIATION IS: 0.9174
THE RRMS DEVIATION IS: 0.1347
DIPOLE MOMENT EVALUATED FROM THE POINT CHARGES
X Y Z TOTAL
0.7833 -0.8856 -0.0014 1.1823
ELECTROSTATIC POTENTIAL CHARGES AVERAGED FOR 
SYMMETRY EQUIVALENT ATOMS
ATOM NO. TYPE CHARGE SCALED CHARGE
1 H 0.0257 0.0365
2 C 0.2079 0.2956
3 O -0.4818 -0.6851
4 H 0.3048 0.4335
5 H -0.0283 -0.0403
6 H -0.0283 -0.0403
TIME TO CALCULATE ESP: 0.12 SECONDS 
FULL COMPUTATION TIME : 0.15 SECONDS
Process Info: 0.3u 0.3s 0:00 60%
|
|
This table lists the Coulson charges predicted by AMPAC based on its analysis of the final density matrix. |
|
|
The series of informational items tell that the ESP procedure is calculating the integrals. |
|
|
This table presents the ESP charges. Note that since MNDO was used as the model, the charges were scaled by 1.422. This is the column labeled "SCALED CHARGE". |
|
|
This line is a count of the number of points on the Connolly surface used in this calculation. |
|
|
As called for by the SYMAVG keyword, the charges of symmetrically related atoms are averaged to account for the asymmetry of the surface. |
|
|
The user should be aware that an ESP calculation can be quite expensive computationally. In this case, virtually all of the CPU time required for the entire job was spent in the ESP routines. STO3G can be used in place of STO6G for a faster (but less accurate) charges. |
|
|
|
|
| Eigenvector Following |  |
Configuration Interaction |
Copyright © 1994, 1997, 2004, Semichem, Inc. All rights reserved. | ||