In pbc calculations for impurity in a supercell, how to minimise the effect of impurities from surroundings supercell images?

Hello, I am a 3rd year chemistry student and I'm writing my project report on computational chemistry. does anyone know how PBEsol improves upon the PBE functional?

Thanks in advance

I am trying to do some vc relax calculations under high pressure(0-40 GPa) on LiC6. Should the 'press' value under the &CELL card be changed accordingly? What is generally the unit of pressure here? Is any unit conversion required?

I am attaching a sample input file for calculations at 40 GPa--

&control

calculation='vc-relax',

restart_mode='from_scratch',

prefix='vc-relax_90_f4e5'

pseudo_dir = './../',

forc_conv_thr = 1.0d-4,

etot_conv_thr = 1.0d-5,

nstep = 1000

/

&system

ibrav=4,

!space_group = 1,

celldm(1)= 8.169834,

celldm(3)= 0.866324,

!a = 4.32329,

!c = 3.74537,

nat= 7,

ntyp= 2,

vdw_corr = 'dft-d3',

dftd3_version = 4,

ecutwfc = 90

ecutrho = 900

occupations = "smearing"

smearing = "gaussian"

degauss = 0.001

/

&electrons

conv_thr =1.0d-8

/

&ions

ion_dynamics = 'bfgs'

/

&cell

cell_dynamics = 'bfgs',

cell_dofree = 'ibrav',

press = 40.0,

press_conv_thr = 0.1

/

ATOMIC_SPECIES

C 12.0107 C.pbe-n-rrkjus_psl.1.0.0.UPF

Li 6.9410 Li.pbe-sl-rrkjus_psl.1.0.0.UPF

ATOMIC_POSITIONS crystal

C -0.0000000043 0.3335500011 0.5000000318

C 0.3335499898 0.0000000001 0.5000000318

C 0.6664500095 0.6664499950 0.5000000318

C -0.0000000197 0.6664499950 0.5000000318

C 0.6664500481 0.0000000001 0.5000000318

C 0.3335499942 0.3335500011 0.5000000318

Li 0.0000000000 0.0000000000 0.0000000000

K_POINTS AUTOMATIC

4 4 4 1 1 1

I am performing an Unrestrticted Kohn Sham (UKS) DFT simulations using cp2k

In my system of 289 atoms, I have 1 Fe atom.

I would like to perform the DFT calculations for different spin states of Fe by varying the multiplicity and find out the ground state spin

Fe has 4s23d6 and for a +2 oxidation state, Multiplicity=2S+1=2*(4/2)+1 =5

Fe can exists in  +2,+3,+4,+5,+6 oxidation states and so corresponding multiplicity is (5, 6, 5,4,1) respectively

But when I input 5 for multiplicity, the program throws an error

When UKS is enabled, it requests a spin polarised calculation using alpha and beta orbitals.

When I did not give any multiplicity, the code provides

which indicates multiplicity =2. Is it the ground state spin state?

Can somebody help me in circumventing this error?

Thank you

Pseudopotentials that are responsive to heavy atoms and best fit to empirical data.

I have tried to optimize Fe(III) high spin complex in ORCA program, but the calculation terminating every time with error. I could not able to find the solution from searches. can anybody suggest me to find the solution for successful calculation.

INPUT

! B3LYP OPT def2-SVP def2/J NormalPrint Grid4 NoFinalGrid RijCosX GridX4 NormalSCF

! SlowConv

%scf

MaxIter 500

CNVDIIS 1

CNVSOSCF 1

Shift Shift 0.1 ErrOff 0.1 end

end

%output

print[p_mos] true

print[p_basis] 5

end

! MORead

%moinp "FILENAME.gbw"

* xyz -3 6

coordinates

*

OUTPUT

************************************************************

* SERIOUS PROBLEM IN SOSCF *

* ------------------------ *

* HUGE, UNRELIABLE STEP WAS ABOUT TO BE TAKEN *

* ABORTING THE RUN *

************************************************************

[file orca_scf/scf2.cpp, line 1377]:

ORCA finished by error termination in SCF

Calling Command: orca_scf FILENAME.gbw b

[file orca_tools/qcmsg.cpp, line 432]:

.... aborting the run

I am trying to analyze the CO2 adsorption on TiO2 substrate. Charge density difference is calculated using Δρ (r) = ρ(r){TiO2/CO2} - ρ(r) {TiO2} - ρ(r) (CO2). Literature have reported that while computing ρ(r) {TiO2} and ρ(r) (CO2), atoms needs to be kept fixed at precisely the same positions as they were in the adsorption complex. However, in my case significant distortion is occurred due to strong interaction between adsorbate and adsorbent, so it will not be possible to maintain the exact same position before and after the adsorption. Is there any alternate approach to deal with it? Any advice/suggestion will be greatly appreciated.

Thanks in Advance!

I am new to ORCA and I just ran a shown test in a tutorial. However, I got an error as follows,

"ORCA finished by error termination in ORCA_GTOInt"

Please help to resolve it.

Thank You.

Dear all!

In DFT supercells are used to study surfaces by introducing artificial vacuum. But some publications use supercells even though they study (infinite periodic) bulk band-structures. Is there a need to use a larger cell (considering PBC)?

I know that in mesoscopic models (molecular dynamics) there is a strong size dependence due to long-range forces, but does the same hold true for DFT (and if so, which potentials?)?

Details from practice: I use Quantum Espresso, (ionic) alloy semiconductors such as GaAs or PbS are of interest to me.

Every comment is greatly appreciated!

Yours,

Chris