Hi all,

I’m trying to perform a single point calculation with ADC(2) and the cc-pVTZ basis, to obtain the first 2 singlet excited states and their transition densities, for a 34 atom system (852 basis functions).

I’ve tried this calculation without the resolution of the identity approximation and the SCF part of the calculation works, but then the next step fails, I’m assuming because of the memory cost of the ADC(2) calculation (> 32 GB).

To solve this, I thought I could specify an auxiliary basis to reduce the memory cost. The only difference between the inputs is the addition of this line to the $rem section:

` aux basis rimp2-cc-pvtz`

This calculation results in the calculation failing with the error:

`line 126: 19741 Segmentation fault ${QCPROG_S} ${inp} ${scr}`

There is no error message printed in the Q-chem output file, but the calculation seems to stop within a second of starting. The last part of the output mentions the number of basis functions in the auxiliary basis, without reaching the SCF part. The last line of the Q-chem output is:

`There are 442 shells and 1286 basis functions`

I have tried repeating the calculation with the same input options and a smaller molecule (chloromethane) to check that there isn’t a mistake in the input. This ran fine. I then tried to run a calculation on anthracene, which failed. I also tried to reduce the basis set size to def2-SVP with RIMP2-VDZ which also failed to run.

Are there any troubleshooting steps I can go through to try and get these calculations to work? I am not sure if these systems are too large for the method or if I am making a mistake somewhere.

This is the input file I am using:

```
$molecule
0 1
H 2.496318000 5.579435000 1.053660000
C 3.404145000 5.039206000 0.813716000
C 3.556114000 4.493421000 -0.456670000
C 4.398258000 4.908217000 1.795344000
C 4.709962000 3.788624000 -0.798407000
H 2.769817000 4.617341000 -1.190637000
C 5.548841000 4.223713000 1.471578000
H 4.255511000 5.337193000 2.779483000
C 5.681855000 3.673939000 0.182562000
H 4.850785000 3.355161000 -1.780609000
C 6.777796000 3.881610000 2.196514000
N 6.893548000 2.996210000 0.097053000
C 7.574598000 3.143905000 1.301068000
C 7.243219000 4.121510000 3.470825000
C 7.461408000 2.478130000 -1.112478000
C 8.822726000 2.640365000 1.629744000
H 6.656254000 4.680514000 4.189623000
C 8.507013000 3.622847000 3.821343000
C 7.275617000 1.116664000 -1.513985000
O 8.094532000 3.382704000 -1.737915000
C 9.281702000 2.898500000 2.921083000
H 9.408673000 2.081190000 0.911168000
H 8.887325000 3.807719000 4.818697000
C 7.865004000 0.748632000 -2.752163000
C 6.580365000 0.087071000 -0.839195000
H 10.254288000 2.531954000 3.224472000
C 7.770892000 -0.521152000 -3.273925000
H 8.406174000 1.514326000 -3.293703000
C 6.477472000 -1.198214000 -1.355563000
Cl 5.793331000 0.346078000 0.711212000
C 7.070563000 -1.497261000 -2.567737000
H 8.235587000 -0.757516000 -4.223032000
H 5.934551000 -1.954825000 -0.804273000
Cl 6.938640000 -3.120066000 -3.216681000
$end
$rem
jobtype SP
method adc(2)
basis cc-pvtz
ee_singlets 2
make_cube_files true
cc_symmetry false
state_analysis true
SOLVENT_METHOD PCM
mem_total 30000
mem_static 4000
ADC_prop_ES2ES true
aux_basis rimp2-cc-pvtz
$end
$solvent
Dielectric 8.93
$end
$plots
grid information and request to plot 2 densities
40 -5.0 11.0
40 -5.0 11.0
40 -5.0 11.0
0 0 2 0
1 2
$end
```

This is the last part of the Q-chem output:

```
Nuclear Repulsion Energy = 2061.32549856 hartrees
There are 87 alpha and 87 beta electrons
Requested basis set is cc-pVTZ
There are 300 shells and 852 basis functions
WARNING: MEM_STATIC is adjusted to be 2000 MB!
Total memory of 30000 MB is distributed as follows:
MEM_STATIC is set to 2000 MB
QALLOC/CCMAN JOB total memory use is 28000 MB
Warning: actual memory use might exceed 30000 MB
Total QAlloc Memory Limit 30000 MB
Mega-Array Size 1956 MB
MEM_STATIC part 2000 MB
Discretize the solute cavity surface with Lebedev spheres
Using 110 Lebedev grid points for each H atom
Using 194 Lebedev grid points for other atoms
Atomic van der Waals radii will be scaled by 1.20
Remove points where switching function is < 1.0e-08
Keep 2345 surface tesserae and discard 3327 interior tesserae
Molecular Surface Area = 346.843 Angst**2
Requested basis set is rimp2-cc-pVTZ
There are 657 shells and 2275 basis functions
```

Thank you for your time.