Hi, Rick, my pdb file is in the standard pdb format:

ATOM 1 OH2 TIP3 1 41.154 -5.264 -51.024 0.00 0.00 WT1
ATOM 2 H1 TIP3 1 41.683 -4.517 -51.303 0.00 0.00 WT1
ATOM 3 H2 TIP3 1 41.779 -5.859 -50.609 0.00 0.00 WT1
ATOM 4 OH2 TIP3 2 37.216 23.916 -58.284 0.00 0.00 WT1
ATOM 5 H1 TIP3 2 36.352 23.916 -58.696 0.00 0.00 WT1
ATOM 6 H2 TIP3 2 37.793 24.313 -58.937 0.00 0.00 WT1

I do not know why it can not be read in.

I defined univer.str with the content below based on the pdb file I posted above:

* define custom format for the water PDB files
*

read univ
* custom pdb
*
unknown
iseq 7 5
type 13 4
resn 18 4
segi 22 1
resi 23 5
x 32 8
y 40 8
z 48 8
w 62 6
!titl 1 4 CRYS
!excl 1 3 END
end

return

and read the file. Then I used the following to read the pdb file,

read sequ tip3 29195
!gener W noang nodihe
gener W setup first none last none noang nodihe
open unit 3 read card name tip3p-1.pdb
read coor univ unit 3
close unit 3
hbuild sele segid W .and. type H* end

The output showed the following error message:

***** LEVEL 1 WARNING FROM *****
***** BILDC called with a null IC table
******************************************
BOMLEV ( -2) IS NOT REACHED. WRNLEV IS 5

I am wondering how to solve the problem. Thank you.