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Questions related to Computational Chemistry
We consider solvent effects to be important for polar molecules, But why are they not important for non-polar/hydrophobic molecules?
15 April 2018 10,163 4 View
Does anyone know how to freeze or fix a specific dihedral in MOPAC? In Gaussian09, you can use the specific command "D 1 2 3 4 F" to fix a specific dihedral. I cannot find an analogous command for...
07 April 2018 3,010 3 View
Dear all, Recently the technology in SDD disk have been developed by increasing the read-write velocities and the "lifetime" of writes such hundreds of TB. Even so, the available memory is very...
07 April 2018 7,052 8 View
Hello, I am trying to calculate the AIM bond orders with Gaussian 09 with the route section: # rb3lyp/6-311g(d,p) scrf=check guess=tcheck genchk geom=allcheck aim=bondorders but the output ends...
06 April 2018 10,064 3 View
I am trying to prove efficient charge separation in a Donor acceptor type conjugated polymer using computational chemistry through DFT calculations. Is there a way to show this ? Also, is it...
27 March 2018 5,458 2 View
I understand that if a given theory for the evaluation of the energy is size consistent, then the energy of the supersystem A+B, separated by a sufficiently large distance so there is essentially...
26 March 2018 6,122 2 View
Is there any keyword missing to get an idea of the dG solvation free energy of a molecule? # M062X/6-31G* Opt SCRF=(SMD,1stVac,Solvent=water) From what I understand from the gaussian09 user...
26 March 2018 1,468 3 View
To model the first bond dissociation energy of a reaction like: MX6 --> MX5 + X I understand HF is not a suitable level of theory as it cannot describe bond dissociation due to its inability to...
18 March 2018 7,330 4 View
Hello, these are graphics generated with Gaussian for an already optimized molecule. Could you indicate from Figure 1, where an electrophilic attack and a nucleophilic attack are most likely?...
14 March 2018 1,168 17 View
Dear colleagues, I am new in the OLED field and just make some research about the field. Therefore I have some questions I want to confirm. I want to investigate the absorption and emission of...
22 February 2018 8,799 23 View
I know some computational chemists who generate many, like a hundred, different conformations of the ligand to dock it the protein. I use Glide, and it considers ligand flexibility. So, it is...
21 February 2018 4,400 4 View
Hello, I'm working on a structure with about 200 atoms. It is important for me to freeze a significant part of it for the time of optimization so that the arrangement of the given atoms with each...
06 February 2018 1,771 7 View
I'm looking to carry out conformational searches of flexible small molecules in the gas phase that I would eventually like to put through quantum chemical calculations. I used to be able to do...
11 January 2018 4,761 2 View
For most theoretical/computational chemists there is very limited chance to get a good job outside of academia, while getting a permanent academic job in this field is also not an easy task. Is...
10 December 2017 9,730 8 View
Dear RG Community, i am new to Gaussian and Computational Physics (/Chemistry). My goal is to calculate the 'IR spectrum' of liqiud Acetonitrile CH3CN (C3V point group) and its isotopologues...
06 December 2017 9,537 8 View
I have one drug candidate in diastereomeric mixture. Is it possible to identify the number of isomers in diastereomeric mixture by using the second derivative calculations and Gaussian curve...
01 December 2017 3,519 4 View
I'm interested in studying interactions between n-hexane molecules and also interactions between chloroform molecules, what are the suggested dispersion-corrected density functionals to study...
12 November 2017 548 27 View
Dear all, I'm looking at the isotropic NMR shielding at different points in space around my molecule employing the so-called ghost atoms Bq. I have created a rather large 2D plane (grid) of 10...
09 November 2017 1,109 3 View
As deep learning, learning algorithm based on multilayer neural networks, which can figure out regularities in huge data (extracted from experiment), and express them in equations; is developing....
07 November 2017 8,520 2 View
Quantum chemistry-ORCA software package. I performed a geometry scan first : ! PBE0 SVP NumFreq D3 TightSCF ! ScanTS %geom Scan B 7 27 = 2.654, 0.9, 40 end end ----> It...
27 October 2017 658 4 View
I have performed an SP calculation on an optimized geometry for the absorption spectra of an organic system. The input was "#p td=(nstates=6) b3lyp/6-31+g(d,p) scrf=(solvent=ethylethanoate)...
07 September 2017 8,565 2 View
I want to calculate a bond order of weak interactions such as VDW interaction and hydrogen bonding. I know some methods for the calculation, but I don't know what should I use.
01 September 2017 3,308 5 View
Hi, I want to perform Energy Decomposition Analysis in a PCM calculations . I found this article Su, P.; Liu, H.; Wu, W. Free energy decomposition analysis of bonding and nonbonding interactions...
01 September 2017 8,872 7 View
Are there any methods to perform the NBO analysis of a complete molecular system as a single unit (metal and ligands combined)? While performing NBO, metal and ligands are considered as separate...
19 August 2017 6,856 5 View