Hi everyone,
I’m trying to perform a VPT2 (vibrational perturbation theory) calculation in Q-Chem where certain atoms are assigned extremely large masses (e.g., 1,000,000,000). The purpose is to simulate “infinite mass” conditions for these atoms.
Here is a simplified version of the input I used:
$molecule
0 1
H 6.6504 4.1522 3.2439
H 5.7711 6.5444 3.2614
…
C 4.2665 5.1347 3.2634
$end
$rem
JOBTYPE = freq
METHOD = b3lyp
BASIS = cc-pVDZ
ANHAR = TRUE
ISOTOPES = 1
sym_ignore = true
SCF_ALGORITHM = gdm
input_bohr = false
mem_total = 60000
$end
$isotopes
1 0
11
3 1000000000
4 1000000000
5 1000000000
…
13 1000000000
$end
However, the job crashes with the following error during the anharmonic analysis:
WARNING! Low frequency modes less than 300 are treated as rotation
No anharmonic shift applied, please see IGNORE_LOW_FREQ for more details.
Q-Chem fatal error occurred in module libmdc/newfileman.C, line 348:
FileMan error: End of file reached prematurely reading (264) bytes in file FILE_TOSH
Is this crash caused by the unphysically large masses?
Any suggestions or workarounds would be greatly appreciated!
Thanks in advance.