How to incorporate the KBFF urea model into a force field in GROMACS package?

The KBFF or Smith urea model is widely recommended for simulations. It has some particular parameters as outlined in the paper attached and it follows the geometric combination rule. In an...

10 November 2019 3,246 1 View

How do you define inter-peptide and intra-peptide contacts/hydrogen bonds in a multiple peptide simulation?

In GROMACS, for calculation of inter-peptide hydrogen bonds, on choosing 'Protein' option twice from the index file (after the gmx hbond command) would give both intra- and inter- peptide hydrogen...

10 November 2019 10,016 3 View

How to implement specific solute models in GROMACS force fields?

In simulations, we often use solutes like urea or TMAO and there have been various differing models for these. For instance, in urea we have the Smith models ( for KBFF as well as the one for...

09 October 2019 4,520 4 View

Is it possible that short peptides may adopt compact conformation in urea solution and extended form in presence of protecting osmolyte?

Contrary to established research,is this kind of opposite behavior possible? Any literature on this? Any ideas how this can be possible?

31 December 2017 6,085 3 View

Hydrogen Bond Lifetimes calculated in gromacs with and without applying pbc are different. Which value should be considered?

07 August 2017 2,674 4 View

Problem with center-of-mass RDF and subsequent coordination number calculation in GROMACS

I want to calculate the COM RDFs between my peptide and water for which I have used the -com option in gromacs.(Also tried with -com and -rdf res_com). It generates a wierd RDF which does not look...

04 May 2017 3,253 1 View

What is the correct way of calculating hydrogen bond lifetime in GROMACS?

11 December 2016 2,067 7 View

Is there any way of calculating hydrogen bond energy in GROMACS?

Is there any information regarding how to calculate hydrogen bond energy in GROMACS?

11 December 2016 3,598 2 View

Correct way of calculating diffusion constant through velocity autocorrelation in GROMACS

I want to calculate the diffusion constant of urea in my system from Velocity Autocorrelation Function using GROMACS. So I used the commands:g_velacc -acflen 1001 -nonormalize -mol -n index.ndx -s...

08 September 2016 3,228 5 View

How can I build caps of the amino acid residues of my peptide (downloaded from RCSB) so as to incorporate into GROMACS?

I want to cap the ends of my peptide chain. Though -ter option of pdb2gmx takes up its zwitterionic form quite easily, I've read somewhere that termini are quite mobile and it is better to proceed...

06 July 2016 7,708 7 View

How to analyze a particular region of my simulation box in GROMACS?

Hi, I am using GROMACS 5.1.4 to simulate water in contact with a surface. I am only interested to calculate some properties of water near the surface. Let's say at a distance of x nm from the...

03 March 2021 9,989 2 View

Polymer composites suddenly solidifies?

I am making polymer composite by solvent mixing method. When I am trying to add filler solution in polymer solution it quickly get solidified. How to make them then uinform? It doesn't give time...

03 March 2021 7,540 4 View

After a reference from Int J Body Compos Res, can any body help?

Hi, I am after the reference below, my library says it cannot obtain a copy either locally or internationally, any help appreciated! Chris Wang ZM, Heshka S, Wielopolski L, Pi-Sunyer FX, Pierson...

03 March 2021 6,193 1 View

Irradiation data for JAPAN?

Hi, Could you help me to get the latest (2019, 2020) solar resource data for a particular site in JAPAN? PV GIS and NSRDB data are not in reach to JAPAN, I'm looking for some other database for...

03 March 2021 961 3 View

What solvent can I used for Paal Knorr reaction between 6-amino hexanoic acid and 2.5 hexanedione?

I am try to make the Paal Knorr reaction between 2.5 hexnedione and 6-amino hexanoic acid, my problem is type of solvent to use, because 6-hexaminohexanoic acid is soluble in water but I am not...

02 March 2021 4,443 2 View

How to repeat an operation on an atom selection for multiple times in PyMol?

Hi, I am trying to construct a multi-layer fibril structure from a single layer in PyMol by translating the layer along the fibril axis. For now, I am able to use the Translate command in PyMol...

02 March 2021 4,569 4 View

How to polymerize TEOS?

I want to polymerize TEOS on a surface. I know that NH4OH is a preferred catalyst and an alcoholic solvent should be used .But I can not find certain amounts of each material to use. Does any one...

02 March 2021 1,404 6 View

How can extract ciprofloxacin hydrochloride disolve in water er to organic solvent such as dichloromethan or any other solvent?

I need a procedure to extract the ciprofloxacin hydrochloride from aqueous solution by using dichloromethane in detail,. I thank you very much.

01 March 2021 4,306 1 View

Can we distinguish the type of free fluid inside the pelvic and abdominal cavities whether blood or serous fluid using the ultrasound?

during ultrasound examination of acute abdomen, sometimes we see free fluid , can we know the type of fluid ,whether blood or not , using ultrasound only? if yes , what are the sonographic...

01 March 2021 7,476 4 View

How to separate water from glycerol solvent in a solvent recovery vacuum distillation column?

I am currently doing my third year design project. I have been assigned to design a glycerol recovery column in vinyl acetate monomer production. The process unit before the recovery column is an...

01 March 2021 9,525 4 View