The geometry of coordinate information is as follow:
Geometry "geometry" -> ""
-------------------------
Output coordinates in angstroms (scale by 1.889725989 to convert to a.u.)
No. Tag Charge X Y Z
---- ---------------- ---------- -------------- -------------- --------------
1 O 8.0000 0.00000000 0.00000000 0.14800000
2 H 1.0000 -0.74000000 0.00000000 -0.59200000
3 H 1.0000 0.74000000 0.00000000 -0.59200000
My grid file ia as follow:
1208 0.0000000000
-2.3432602255 -2.8345889818 -5.8430327549 0.0164028207
I have read part of the "esp_esp.F" file's source code in NWCHEM 6.0:
do 8 i=ngfr,ngto
vt=val(i)
imin=0
do 9 ix=1,natoms
dist=sqrt((grid(1,i)-x(1,ix))*(grid(1,i)-x(1,ix))+
+ (grid(2,i)-x(2,ix))*(grid(2,i)-x(2,ix))+
+ (grid(3,i)-x(3,ix))*(grid(3,i)-x(3,ix)))
if(imin.eq.0) then
dmin=dist
imin=ix
endif
if(dmin.gt.dist) then
dmin=dist
imin=ix
endif
val(i)=val(i)+q(ix)/dist
9 continue
if(me.eq.0.and.util_print('where',print_debug)) then
if(i.eq.1) write(lfnout,1003)
1003 format(//,' Electrostatic potential on grid',/)
write(lfnout,1004) imin,i,(grid(j,i),j=1,3),val(i)-vt,vt,val(i)
1004 format(2i5,3f8.4,3f12.6)
endif
8 continue
So I think " -2.3432602255 -2.8345889818 -5.8430327549 " are the "grid(1,i), grid(2,i), and grid(3,i), " 0.0164028207" is "val(i)"
And " 8.0, 1.0,1.0 " is "q(i)"
Therefore, I calculate the distance ("dist" in esp_esp.F) between the grid and "O" is 7.029811 angstrom, the distance between the grid and first "H" is 6.178890 angstrom, , the distance between the grid and second "H" is 6.716750.
and val(i)=8.0/7.029811+ 1.0/6.178890+ 1.0/6.716750=1.448734. But the value in grid file is "0.0164028207".
So, I want to know what is wrong with my calculation methods?
Another question is what is the meaning of " 0.0164028207"? And what is the unit of " 0.0164028207"?
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