$ECP group (required if ECP=READ in $CONTRL)
This group lets you read in effective core potentials, for some or all of the atoms in the molecule. You can use built in potentials for some of the atoms if you like. This is a free format (positional) input group.
*** Give a card set -1-, -2-, and -3- for each atom ***
-card 1- PNAME, PTYPE, IZCORE, LMAX+1
*** For the first occurence of PNAME, if PTYPE is GEN, ***
*** then give cards -2- and -3-. Otherwise go to -1-. ***
*** Card sets -2- and -3- are repeated LMAX+1 times ***
The potential U(LMAX+1) is given first, followed by U(L)-U(LMAX+1), for L=1,LMAX.
-card 2- NGPOT
NGPOT is the number of Gaussians in this part of the local effective potential.
-card 3- CLP,NLP,ZLP (repeat this card NGPOT times)
CLP is the coefficient of this Gaussian in the potential.By far the easiest way to use the SBK potential for all atoms in the formic acid molecule is to request ECP=SBK in $CONTRL. But the next page shows two alternatives.
The first way is to look up the program's internally stored SBK potentials one atom at a time:
$ECP C-ECP SBK H-ECP NONE O-ECP SBK O-ECP H-ECP NONE $END
The second oxygen duplicates the first, no core electrons are removed for hydrogen. The order of the atoms must follow that generated by $DATA. Note PTYPE allows you to type in one or more atoms explicitly, while using built in data for some other atoms.
The second example reads all SBK potentials explicitly:
$ECP C-ECP GEN 2 1 1 ----- CARBON U(P) ----- -0.89371 1 8.56468 2 ----- CARBON U(S)-U(P) ----- 1.92926 0 2.81497 14.88199 2 8.11296 H-ECP NONE O-ECP GEN 2 1 1 ----- OXYGEN U(P) ----- -0.92550 1 16.11718 2 ----- OXYGEN U(S)-U(P) ----- 1.96069 0 5.05348 29.13442 2 15.95333 O-ECP H-ECP NONE $END
Again, the 2nd oxygen copies from the first. It is handy to use the rest of card -2- as a descriptive comment.
As a final example, for antimony we have LMAX+1=3 (there are core d's). One must first enter U(f), followed by U(s)-U(f), U(p)-U(f), U(d)-U(f).