Questions tagged [computational-chemistry]

For questions about computational chemistry.

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7
votes
0answers
37 views

What are the methods of modeling Jahn-Teller effects in a solid-state material?

The Jahn-Teller effect arises from the symmetry breaking (distortion) of the local environment for the crystal field of 3d transitional metal ions.The distortion result in energy saving of electronic ...
6
votes
1answer
53 views

I get an error 'Conversion from Z-matrix to cartesian coordinates failed' in Gaussian09. Any suggestions?

I'm doing my calculations using G09W. My OS is Windows 7 (64-bit). This error occurs in the frequency calculation. What's even weirder is that it seems to happen right after everything is already ...
6
votes
1answer
25 views

I get this error in Gaussian09 even though I have enough memory. “Error termination in NtrErr: NtrErr called from FIOCnC.” Any suggestions?

Whenever read-write files get to about 20Gb, I get this error. I know that, in G09, one rw file is limited to 16Gb. So I have set the software to write several RWFs. But it still keeps producing this ...
13
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2answers
377 views

How well can we model chemical synthesis?

The Materials Genome Initiative held a 2017 workshop, that led to this published report: de Pablo et al., "New frontiers for the materials initiative," npj Computational Materials 5, 41 (...
13
votes
4answers
130 views

What is the role of a chemist in computational chemistry?

As someone that wants to learn about computational chemistry, mainly for its use in energy storage materials (and therefore DFT as the most practical method of it), I am wondering what is essential ...
11
votes
1answer
74 views

Calculate spin-spin coupling based on previous GIAO calculation with Gaussian

I used GAUSSIAN/GAUSSVIEW to calculate the GIAO Magnetic shielding tensor (ppm), but I forgot to calculate the Nuclear spin-spin coupling J (Hz). How can I use the .chk file or .log file to calculate ...
14
votes
1answer
206 views

How can I scan the whole PES of a bulk structure?

I am not very familiar with scanning a PES for a bulk structure, and I'd be very appreciative for some suggestions.
13
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2answers
115 views

A CCSD(T) geometry optimization in Gaussian09 is deviating too far from the minimum. How do I deal with it?

I am doing a CCSD(T) geometry optimization on a series of molecules. One of the geometry optimizations took about 2 weeks even though an analogous molecule with the same number of basis functions took ...
16
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6answers
248 views

What are the applications of chemical graph theory?

Graph theory was originally introduced in computer science to study data structure. Chemists also introduced graph theory to study the relation between structure and properties for molecular compounds....
8
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1answer
91 views

The correlation energy from frozen natural orbtials (FNOs) using CCSD and MPBT(2)?

In other works and from the paper: Scaling Up Electronic Structure Calculations on Quantum Computers: The Frozen Natural Orbital Based Method of Increments. I have seen that the corrected CCSD ...
10
votes
2answers
191 views

One-center two-electron integrals between 1s STO

As per @user1271772 's suggestion I am asking this question here again. I am trying to understand SCF cycle by trying to code up solved example from Quantum Chemistry by Levine (page 443, 5th edition)...
14
votes
1answer
119 views

How the projected density of states is built

I'm new to DFT. I'm trying to figure out how projected density of states (PDOS) is built in solid state physics software package. I understand the basics of the density functional theory method: each ...
12
votes
1answer
79 views

What is the impact of the orientation of a molecule in cartesian coordinates to molecular properties?

According to my knowledge, each computational chemistry code optimizes a molecule keeping the input orientation of the molecule. The population and spectral analysis is performed on the optimized ...
9
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0answers
73 views

Is there any literature that systematically analyzes current quantum chemistry algorithms using Big O notation for time and memory cost? [closed]

Big O notation is commonly seen in the papers on novel computational methods. However, only a few of them include rigorous analysis of the algorithm. Is there any literature that summarizes current ...
23
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2answers
2k views

What are the “smart algorithms” applied to solve the “curse of dimensionality”?

The "curse of dimensionality" is an ubiquitous issue arising in both electronic structure and quantum molecular dynamics, which refers to the exponential scaling of computational cost with ...
15
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1answer
174 views

CCSD(T) Transition State and Ground State Calculations in Gaussian09: “Unable to Determine Lambda”?

I’m doing CCSD(T) calculations (for both transition and ground state geometries) on a series of small molecules in Gaussian09. Several similar calculations terminated without any problems but one TS ...
8
votes
1answer
64 views

What chemical systems can be modelled without the use of approximations? [closed]

Because of its size, for example a protein can not be modelled from the quantum chemical basis in a reasonable amount ot time without approximations. A hydrogen atom though can, manually even. Where ...
19
votes
3answers
226 views

What software is needed in chemoinformatics or materials modeling, that a solo programmer could work on?

I want to make a pet project in cheminformatics and I need to hear from the community about the actual challenges in chemistry that might be resolved with a digital solution. I've been working in ...
24
votes
1answer
245 views

Approximate equivalence table between Pople's basis sets and Jensen's DFT optimized polarization consistent basis sets (pcseg-n)

At first I posted this question in chemistry.stackexchange.com, before materials.stackexchange.com was launched in beta. As it went unaswered, I'm giving a try here. I have some calculations results ...