The total binding energy in SAPT energy decomposition turns out to be positive

SAPT
1

I make an energy decomposition analysis in the complex LaCl3H2O. The structure has been optimized. By performing the SAPT calulation, I want to evaluate intermolecular interaction energy between LaCl3 and H2O. The input file is shown below,
memory 200000 MB

molecule dimer {
0 1
La -1.245901 -0.030094 0.049950
Cl -2.495563 2.194252 -0.517413
Cl 1.386678 -0.062614 0.280512
Cl -2.525909 -2.306411 -0.142389

0 1
O -0.908811 -0.341351 2.578561
H 0.039773 -0.403213 2.763659
H -1.365765 -0.963412 3.157789
}
dimerdist= 2.569900

set {
basis def2-qzvpp-ri
scf_type DF
freeze_core True
}

energy(‘sapt2+(3)dmp2’)
E_disp = get_variable(‘SAPT DISP ENERGY’) * psi_hartree2kcalmol
E_elst = get_variable(‘SAPT ELST ENERGY’) * psi_hartree2kcalmol
E_exch = get_variable(‘SAPT EXCH ENERGY’) * psi_hartree2kcalmol
E_ind = get_variable(‘SAPT IND ENERGY’) * psi_hartree2kcalmol
E_tot = get_variable(‘SAPT TOTAL ENERGY’) * psi_hartree2kcalmol

psi4.print_out("\n")
psi4.print_out(" Summary of SAPT result (kcal/mol)\n")
psi4.print_out(" Distance E_tot E_elst E_exch E_disp E_ind\n")
psi4.print_out("%s %6.3f %10.3f %10.3f %10.3f %10.3f %10.3f\n" % (“R=”,dimerdist,E_tot,E_elst,E_exch,E_disp,E_ind))

However, after calculation, it is found that the total binding energy is positive, as shown in the picture attachment. Is it because of the basis set used for La?
I want to know what is the reason and appreciate it If anyone knows how to solve it. Thanks!

QQ%E5%9B%BE%E7%89%8720190711172040

2

You need to use standard orbital basis sets! The auxiliary basis sets (-RI/-JKFIT) will be added automatically. If you use them as main orbital basis sets many problems will arise.

Try
basis def2-QZVPP

3

Thanks for your reply. That is so kind of you! I have tried def2-qzvpp before. But an error is encountered, as shown in below,

1
1.png1437×490 18.4 KB

Do you know the reason? Please grant instruction!

4

Do you have enough space in the your scratch directory? Did you specify one? The default (for Linux) is /tmp and the can have limits.

5

Sorry for this late reply. /tmp is located in a disk that has over 400GB empty space. And it should not be limited. I think the problem is still on the selection of basis set.

6

Have you started with SAPT0 rather than the high-order 2+(3)? energy('sapt0/jun-cc-pvdz') will stress your computer least and be quicker to diagnose problems. You really have 200 GB memory?

7

Thank you for the reply. I have found the problem and solved it after I read the post entitled ’ SAPT with ECP for Iodine atom’. I reset my basis set to
set globals {
basis def2-tzvp
df_basis_sapt def2-tzvp-ri
scf_type DF
}
Then it can proceed and end normally.
PS. I do not have 200 GB memory. It is supposed to be 20GB. It a clerical error but not the problem.

8

One more question. In mannual, it is said that the default auxiliary basis set for SAPT density fitting computations is a RI basis. There are many kinds of Auxiliary basis sets. Can I use other ones, for example jkfit basis, in my calculation?